I've started tossing in something like 10x150 on 3:00, with the first 50 being "all out", for best average, and feel like its helped me tremendously; I can use blocks and get water "comfortably" (ie, I've got plenty of time, but am anything but comfortable).
Of course then I started training with my ex-collegiate sprinter buddy, and realized how much of a minnow I am outside of age group multi-sport when he swam sub-22 from a flat start with paddles.
edit: Should be noted that I do something like 10x100 or 15x100 in the same workout as these 150s, so while they're quality, they're definitely not like the good old days of yore when we'd do something like 2 or 3x100, and you had to get within some range of the PR, or dryland extended a half hour and involved more pushups than any human can do.
Of course then I started training with my ex-collegiate sprinter buddy, and realized how much of a minnow I am outside of age group multi-sport when he swam sub-22 from a flat start with paddles.
edit: Should be noted that I do something like 10x100 or 15x100 in the same workout as these 150s, so while they're quality, they're definitely not like the good old days of yore when we'd do something like 2 or 3x100, and you had to get within some range of the PR, or dryland extended a half hour and involved more pushups than any human can do.