Add the ability to set up days when client is supposed to train, but queue workouts instead of fixing them to a date:

Example:

I want my trainee to workout on Monday, Tuesday, and Friday.

I want him to do two workouts A and B.

Right now i have to set it up on a fixed day:

Monday: A progression 1
Wednesday: B progression 1
Friday: A progression 2
Monday: B progression 2
etc.

If he misses Wednesday's workout he should do "B progression 1" on Friday instead of "A progression 2".

No I have to change everything manually, and change date of each progression of the workout.

It would be awesome to be able to set:

Workout days: Mon, Wed, Fri.

Workout queue: A1, B1, A2, B2

So you can progress to the next workout only when you have finished the previous one.