Here is a race week swim - (1 week out or the Monday before a Sunday race):
This would be your last real hard swim 1 week out from an A race on Sunday. This workout hits all the key components as you're tapering. A good warm-up with technique work; a fast pre-main set with fast 25s; fast 50s to work on get out speed on race day and 100s done quickly at race pace.
Modify as needed for athlete's yardage needs
2-3x(200 free + 100 drill) * moderate descend on the 200's as you get warmed up; * drill as 25 rt arm/25 left arm/25 fists/25 catch up
12-16x25 as 3 FAST/1 easy on :30 or :40; 1-8 swim, 9+ swim w/ fins
200 aerobic swim or pull w/o paddles
9-12x50 as 2 FAST/1 easy on interval with at least 20 SR150 aerobic swim
4-6x100 as odd race pace/even aerobic on interval w/ 20-30 SR100 aerobic swim or pull
200 as 25 FAST/25 easy
D3 Coach Susan Williams has led many athletes to Race Day PRs