Single Pilot 135 Cargo. Unfortunately it's on the job training by yourself. You learn real quick through trial and error what your and the airplanes limitations are. You push the limit to far and drill a hole in the ground, than you become another statistic instead of breaking news on CNN. Nobody cares about 1 dead pilot and a bunch of boxes or checks.

Is it an imperfect system? Yes.

Does it produce the seasoning and experience that your describing? Well that's up for debate.

Will you draw on those experiences for the rest of your flying career? Most definitely.