work out configuration question

with 3 kids under the age of 5 and working full time I have only 4 workout sessions a week to split between running and biking.

should I do

2 runs and 2 bikes a week

or

3 runs and 1 bike one week  and 3 bikes and 1 run  the other week.

Right now am doing 2 and 2 but I know from past experience I gain more by doing 3 or more like workouts  in the same week.

currenntly I run about 15 miles a week and bike about 60 miles a week and am working towards sprint distance races