With regard to remote holding we are sometimes guilty of starting you up a little too late to get airborne in the first few minutes of your slot window. This does get noticed and conversations had so we are trying to improve!
On the other hand it is not uncommon for us to approve your start and be told that "we would like to wait another 5 minutes".
With it being very busy now both these scenarios occur with little time on both sides to get into a discussion about earliest airborne times and how busy it is at the hold etc.
Personally I take it as a personal failing if I don't get you to the hold in order to be airborne as close to -5 as possible.
If you started with no delay I'm afraid it's luck of the draw. Anytime between -5 and +10 is acceptable if using the runway to its max and departing as close to start up request order as possible.