I always use drains after a Tummy Tuck. I do so to try to avoid a seroma or fluid collection which requires repeated needle drainage.
All Plastic Surgeons are taught that a drain can be removed when the output of drainage is less than 25 cc in a 24 hour period.
The risk of leaving a drain in longer than 5-7 days is that tissue can grow around the drain inside the abdomen and create a cavity around the drain (synovial membrane) which could continue to produce fluid and require repeated needle punctures to remove fluid and eventually require surgical exploration to remove the synovial cavity.
The duration of surgery, surgical technique, and the health of the tissues have a lot to do with the amount of drainage post op. Short duration of procedure, careful fastidious technique with minimal tissue destruction and minimal bleeding will reduce the amount of drainage and allow for early drain removal.
Excess bleeding prolongs drainage. Attempting a Tummy Tuck before adequate weight loss, that is operating on the obese abdomen will also increase drainage.
If excessive drainage persists past 5-7 days then your surgeon will have to weigh the risks of leaving the drain in versus the need to do aspirations of fluid after drain removal if a seroma occurs.
In my experience careful surgical technique on properly selected Tummy Tuck patients usually allows me to remove drains by 5-7 days.