I try to get in 3-5 at a regular practice (not pre-competition)... If it's the last 1 or 2 practices before competition, I have them do 1 to start off with and evaluate from there. For instance, if the pyramid crapped the bed, and tosses were ugly, I would spend 5-10min working those elements and then have them run it with just those two elements. (we never mark jumps or dance/motions) Sometimes I will say, no running tumbling or only running tumbling or whatever needs fixing.
We will usually spend 2 hours doing piecemeal runthroughs- Ill give them a few minutes in between or spend time on whatever needs time, and then run it again. Out of the whole 2 hours, I probably only get about 5 that are completely fullout. I always ask for one fullout before they leave, and sometimes they're just so tired by then that I wont ask for it again if it doesn't go perfectly. I'll just run the sequences that didnt hit individually and send them home.
In general, I try not to make changes the week of a competition. I just like to use that week as fullout conditioning and cleaning.... This is why I prefer to have at least one weekend off between competitions, so we can determine what changes need to be made and have a whole week to practice them... unfortunately, my gym owner loves to schedule 2-3 weekends in a row at times, so it gets hard to progress the routine properly imo... I'm left with 2 practices to make 3 weeks worth of changes, and it's overkill at times, so I don't get to make the necessary changes... but, I digress...
To answer the question, 3-5 FULLOUTS and twice as many runthroughs doing just pieces:)