4 swim day or longer swim sessions?

It can work either way, but you also have to make sure you get some intensity in those yards.  You could do 2 days of 5k each, but if you're cruising for most of those yards, it won't be as good as 4 days of 2.5k where you're hammering out intervals.

Also, if time is a limiter, I found that being more efficient with your workouts allows you to get much more yardage in a given amount of time.  Get in the pool, get on with it, minimize your rest breaks, don't stop to chat with others, get out, shower, and go home.  Maybe you already do this...most average swimmers at the pool don't.

If additional time to & from the pool isn't an issue, I like the extra workout more with the size of your swims (2,500-3,000). At your pace, that will be plenty of hard work even with a big warm-up to get ready. The additional frequency will help both in improving skill and in (potentially) more work at a harder effort.

Do be mindful of how the lifting affects the swim. Know what your priorities are for that. I just remember from when I was still lifting a few years ago that swimming around the lifts rarely went that well.

Are you doing sets, like 20 x 100 or just swimming until you reach your designated mileage? Are you doing 1:50/100 as a stand alone sprint or is this your pace when you do  your sets? 

I really liked doing this set: 8x25, 4 x100, 2 x200, 1x400. Sprint the first 25, recover the second, sprint/recover/sprint/recover etc by the 2x200 I usually just swam the rest at a race pace. Only take 10-15 seconds rest if needed. As you get more efficient you can sprint more and recover less.

On longer swim days I would do 10x100 go on 2min, the above set, and then another 10x100.

I'm in the group of people that believe swimming faster more often will make you faster overall rather then just swim slow with a lot of mileage. Swimming very long sets has its place, but not as the bulk of ones swim workout. 

Less warm up and drills and do more hard swimming so you are panting on the side of the pool, feeling you gave it your all.

Doesn't look like you do much hard swimming.

I find 4th swim is better than longer swims.

I used to lift and swim on the same day and found it worked really well for me. I think some days I lifted during lunch and swam after work so they were not back to back.

x2

I would use caution adding a swim session after a weight session.  The absolute first priority should be proper stroke technique.  If you stroke breaks down from fatigue (much more likely immediately after a weight workout, especially if you don't have a coach on deck to observe) the extra swim workout would actually be detrimental.

As an extension to the OP's question, would you all recommend jumping right in to full on intensity and just letting your body's limits set the bounds for the workout by what it is capable of, or do you build intensity into the plan more slowly?

I've been back in the pool in ernest the last few weeks and have been swimming what would be considered, to most of you I would guess, junk yards - going at less than race pace but a decent clip (for me) for 2-2.5k per swim.  I've approached it like running or biking, where I build a base and THEN add in intensity (acknowledging that you can put more intensity into swimming more regularly - that's not my question… it's when to start and how fast to ramp).

Having had my right shoulder "fixed" surgically, I don't want to pop my left one!  Is this something I don't need to worry about?  There aren't issues with it currently, but I've been thinking about it as building endurance for a couple months and THEN adding in the intensity.  Should I just start doing vomit inducing sets right now?

I love long, hard OWS workouts, but in the pool (and almost anywhere else) I'm a sucker for getting all sprinty and have actually been holding myself back and trying to be smart (for a change).

Matt

Well, I wouldn't jump right into the vomit inducing stuff but I certainly wouldn't build for months.  Start adding the intensity now but keep it smaller and build that.  Start with 10x50, or even 2 x (5 x 50) with an extra minute or two between the 5x.  Pick a pace and repeat time that you can hold for the whole set but gets you tired by the end.  Go from there.