Well consistency is the key edging a minimum of two days per week should help build up stamina. When you kegel it also improves blood flow. Kegeling is an activity you do while edging. The longer you sustain an erection the bigger it seems to get. This is due to more blood flowing into the penis while erect.
So it is the actual kegeling while edging, rather than edging (if you didn’t kegel while doing it) that is increasing blood flow, right?
You also said that there is more blood flowing into the penis that is erect for a long time while edging, however, this is only temporary, right? It’s not like edging will give you permanent blood flow.