Understand, "going solo" in the context of primary flight instruction does not imply authority to go hop in the plane at will and blast off into the wild blue. The first 3 - 5 solo flights are supervised solos that start off as dual instruction and then have a solo session incorporated under the strict observation and supervision of the instructor. Five hour solos were not routine or common, but an exceptionally adept student could achieve it if they could absorb all the requisite skills in that amount of time. And if you're operating from a low traffic rural airport with enough different runways to handle a variety of wind conditions the occasional talented student could do it, if old man weather cooperated. YOU wouldn't have soloed in five hours, even if the skill set was in place, because you wouldn't have been mentally ready and I wouldn't have made that call. I've had students that were "ready" skillwise to solo in seven or eight hours, but didn't have the confidence to be mentally ready until they were up to twelve or more. These were often of the perfectionist persuasion, and made some of the best pilots in the end.
The FARs delineate what a student must be trained before they can solo, and I always threw in a few "extra" emergency procedures. They best be on their toes, as every .7 or .8 hour lesson would have at least one emergency of some kind.
Before takeoff checklist complete, pattern clear, position and hold, think, "This is the time the engine will quit 200 feet over the departure end; what am I going to do?", before every takeoff.
"Oswego traffic, Cessna seven five seven Bravo Yankee, left crosswind one six, departing east to the practice area." Now if the engine quits right here, where am I going to park this bird?
Bear in mind, my instructing days were in the 70s and 80s, when tort law was not so all-pervasive as it is today. Today I would probably be a little more restrained with the talented super student. Even then, none of mine soloed without first demonstrating a spin recovery, which was above and beyond the FARs.
Cheers,
Wes