Calling all fish!

There is a big difference between swimming your fastest (or faster) 100s vs. swimming your endurance pace 100s.

it sounds like Matt's plan wants you to swim your 100s at your endurance pace with 5 seconds rest. This makes sense because any faster pace will require more rest time in between. So...swim at the fastest pace you can sustain through the entire set of 100s with only 5 seconds rest...keeping the first & last sets the same pace.

There is a lot of value i swimming a lot of repetitiosn at your endurance pace even though you could swim the shorter intervals much faster (if given more rest). What you want is to become the most efficient you can be given the distance you are training for...not the fastest swimmer for 100s with lots of rest.

having said that, there's nothing wrong with swimmign fast 100s if that's what your workout or overall plan calls for...but generally you'll need more than 5 seconds rest. If you are sprinting 100s, you'll ideally need 3-5 minutes rest to be able to repeat the same fast sprint.

it all depends on what you want to work on.

it sounds to me like you need to slow down a bit, so you can swim evenly paced. as you get more swim volume in, your speed should naturally improve as you are training your technique at a certain pace.

also, dont forget to read the 21 laws of swimming thread.

I am not familiar with the goal of the workout and what kind of intensity you need to sustain, that might make a big difference. That said, like 5 years ago I read some articles about Joel Filliol about swimming how while swim technique is important, there was an exaggerated emphasis on technique and not so much on swimming more at different load (duration+intensity)

At the time I was like a ~1:40 min/100yds swimmer, so one of my weekly swims become focused on speed regardless of fatigue or my 'form' breaking down. I began doing 8-10x 100 @ critical swim speed (CSS) aka threshold w/ 5-10 sec rest. I would do this as long as I could maintain the speed and rest interval. When I simply lost speed or couldn't recover on time I would stop and resume my session swimming easier. The next week I would shoot for at least 1-2 more intervals until I built up to 20 x 100 @ CSS w/5 sec rest.

I didn't care if my form would break, over time it become obvious to me that my technique would deteriorate due to fatigue. Also, by pushing my speed as I would get tired, it forced me to become more aware of my stroke to sustain the same speed with 'less' effort. Over the next months I went to become more of a 1:20 min/100yds swimmer because my endurance and technique improved.

The reason why I mentioned the above; if Matt's workouts have that goal the to answer your Qs:

1. it is important as it will force your body to adapt, still if at 1st you can't sustain the speed or recover on time try making rest a bit longer and build up to be able to only rest the suggested interval
2. yes if you are consistent
3. it is not wrong, as mentioned at 1st it might be good.  But by building up to do sets with less rest you'll build your speed and endurance. 
4.  it is important to focus on technique, but also on endurance and speed.

It sounds like you've set your base interval too fast.

Open your favorite internet search site & search "swimming determining base interval"
you should get several hits --- one is a google books link to a Janet Evans book & she discusses determining base intervals and the reasons for the 5-10 second rest.

Good luck

Dan

You got excellent answers above. I will just expand on them a little. Also, no matter what we come out here with, stick to your plan as long as it is working, no need to change.
5sec recovery or as a part of the base interval promotes endurance swimming. The 100 set you mention is to be done at even speed, endurance pace. Short recovery prevents you from swimming any faster. That is usually the intent of a set like that. 100y/m endurance sets are not your best bang for the buck if you are beyond an initial stage passed first 4-6 weeks. The interval distance recommended would be 200y/m and beyond, the more advanced, the longer your race distance is, the longer they get. 100y/m is used as an intro to endurance work as well by coaches who manage crowded lanes with swimmer as it is easier to keep swimmers from running on top of each other.
The progressive overload in an endurance set as listed above should go in the direction of increasing the number of 100s, 10, 12, 15........rather than swimming them faster. Endurance is what they are working on, so keep your endurance speed and don't escalate it there, you should be able to complete them all at same speed, slow down the early reps.
If you were to follow a natural progression in endurance sets, include 5x200 to start, base pace+5sec per 100 for your send off, you should end up with 10sec of rest for 200s, than 300s....400s......keeping your base pace/speed over longer distance.

1. Important for endurance work, keep it, slow down to finish even and strong.
2. If you only keep swimming 100s at endurance interval, no, you have to extend the interval as indicated above.
3. It is not wrong, you will just be entering a different energy system work, if the plan calls for it, do it. 10sec recovery per 100y/m helps promote threshold speeds, 10x100@1:30 touching in 1:20 every time could be your threshold work, longer recovery/ faster speeds, again even and strong, no fade.
10x100@1:40 touching in 1:15 is a typical beginners VO2max set, more recovery, but swimming at much faster speed. In swimming recovery time indirectly manipulates intensity.
4. You are missing longer endurance sets that would amount to total work of 30-40min, 2000-3000y MS divided in say 5-7x200(10sec), 4-5x300(15-20sec), 4x400(20-30sec)......
10x100(10sec)@threshold, extending those down the road..........
Since you are doing a plan, just stick with it. If it is well put together, it should account for this.

Where can i find the "21 goals of swimming" thread?  Thanks.

Wow!  A treasure trove of information.  Thanks so much everyone.  I am clearly not doing an endurance pace when doing the 100 intervals.  Still being quite new to swimming I am having difficulty with the pacing.  I have two speeds: a leisurely warm up and cool down pace & a swim hard and fast pace.  I will look up those suggestions to find a pace somewhere in between to find my endurance pace.  Makes sense for running, I don't know why I treat swimming like "rocket surgery". 

Again, thank you.  This truly is an awesome place with very talented and generous people.