the 1000 block workout
1000 warm up swim - build, perhaps every 4th length stroke (1000)
10 x 50 pull
10x 50 kick (together, all 50's = 1000)
5 - 10 x 100 descending OR pattern (3 fast, 1 recovery, etc) (500-1000)
Total: 2500 - 3000
I also like 400 blocks when I want to increase my workout meterage like so:
400 swim warm up (400)
8 x 50 pull (400)
2 x 200 IM kick (400)
3 x 400 swim, pull, swim by 400
400 pace, 4 x 100 fast and repeat
etc. its easy to come up with 400m chunks and sometimes 400m seems an eternity less than 500m for some reason. its all mental.
I can make intervals (the time I have to swim each rep) longer or shorter. but always, unless it's warm-up, drills, or recovery, its important for me to have a goal and work at an 85% level or better. so i make up my intervals with this in mind. Interval training is important for SO MANY reasons, but - and I can't state it enough- you can't see your progress if you don't break it down. Sure - maybe you can swim 1,000 meters straight. but are you holding a slower pace than you think? is your technique failing? are your turns slowing? let's say your pace is 1:45 per 100m. if you did 10 x 100 on 1:50, attempting to hold 1:45 or better -- you can see exactly where you start to fail and why. you have time to notice the details. you will also be able to see when you start to go faster than 1:45. it's a sure way to see if your training is making you faster or not.
So, I tend to do the same sets. I know what I need to work on and repeating and perfecting the same sets keeps me honest.