There really is no general answer to your question except that it depends on a lot of variables, like temperature, resin viscosity and what you want to accomplish. Sometimes debulk is used to minimize voids in the part, in which case a 24 hour debulk can be beneficial. With phenolic resins the main reason for bebulk is to prevent wrinkles due to compaction, in which case 10 or 20 minutes might be sufficient.
Develop a measurement that will tell you that you have accomplished what you want from the debulk process. If you don't know why you are debulking, perhaps you do not need to do it at all.
One common mistake done during debulking is to bridge bagging materials over the edges of parts. This will cause a compaction pressure intensification on the part edge which will pinch-off breathing paths, contrary to what a debulk is for.
