One evening during the National Division 2 competition in the University of Limerick I met up with a bunch of Limerick Masters swimmers for a training session. We did our own warm ups, then they suggested this pyramid of hundreds. I have left the times as we did them, my swimming season hasn’t started yet so I’m out of shape, I came in on 1:15 for almost all of them which really pushed me. When doing this later in the season I will probably adapt it so that the last set of 6 is 5 seconds under my regular “off” time for 100s (e.g. if I’m normally doing them off 1:30 the last set will be 1:25) and aiming to come in on 1:12s. There is no break between sets of hundreds.
To finish the session and to get an extra 300m in I suggested the 75s, which I’ve also used in another session on this site.
I am available if any other Masters clubs are interested in having me join them for a training session (and writing it up here if they like).
The usual disclaimers apply, this is an example of a session I swam, you are free to have a go or adapt it, but do so at your own risk & under your own responsibility etc.