No prewet and no stop. Those are two critical factors especially with large format and hand agitated in a drum as well. It takes time for developer to spread evenly across a dry sheet of film or paper. It spreads more smoothly over a wet sheet. Same thing with stop. It takes time for water to neutralize developer evenly. Acid does it quickly.

These problems are worse at short development times. Kodak mentions that in their B&W darkroom dataguide.