You are misunderstanding what I am saying
@PhatD1ver.
Any rigid system can 'break', not having one cannot.
For example: any routine you might have developed is broken on decent as soon as you add a third tank.
There is no real reason why you should not switch regs several times in any interval you might set, but a lot of reasons to not be able to do a comfortable switch at any one certain point in time (forcing you to postpone it).
Not using rigid intervals reduces the need for exact calculation and the resulting taskload.