There is a decent list of rules and guidelines for group cycling but there isn’t much for swimming.
Given how crowded the lanes get this time of year I propose the following for a start
Mind the gap
Leave a reasonable gap between you on the next swimmer. 3 to 5 seconds, depending on how busy the lane is. Try to be consistent. If you decide to add or remove an extra couple of seconds after a number of intervals you are forcing everyone else behind you to do the same.
Hit the wall
Start at the wall, finish as close to the wall as you can. If you slow as you approach the end of a interval and walk the last few meters you are forcing the person behind to do the same.
Don’t be a Sunday driver
If a gap is opening between you and the swimmer in front and the swimmer behind is on your toes or just maintaining the usual distance from you its time to move to the side and drop down a position. Maybe one of more people behind you could keep the pace of the guy in front.
Tortoise and the Hare
Maybe you have the speed to hold a particular postion in the lane for the first couple of intervals of a set but then fade.
As you slow you become the Sunday driver above.
Ideally pace yourself at a level you know you can maintain.
Recognise if you are fading and drop a position of two.
Bare in mind if you do this you are interrupting the pacing of those behind you. e.g. they may now lose a few seconds rest.
Toe fetish
In a busy lane getting touched on the toes is occasionally inevitable.
If you find your toes are being fondled ask the person behind you if they would like to go ahead on the next interval.
The toe toucher should either move up or leave their toe fetish for the bedroom.