If I have a deadline, I use a very simplified quilting pattern. I'm working on one now that is simply round circles with arc's in them to resemble softballs (there is a purpose/reason here). Each one takes me about 45 minutes to do. I'm using W&N batting so I'm fortunate that I don't have to quilt too closely. These are scattered randomly throughout the quilt. It's an oversize twin. I need to be done by mid-June. I only started the quilting a couple of weeks ago but feel I can manage this timeline.
Most of the quilts I do are what I refer to as 'milestone' quilts...birthdays; anniversary; graduation; and they are all bed-sized. I know those deadlines long in advance. I usually start from scratch about 9-10 months out depending on the time of year for the deadline.