i dont jobo, i use tray dev but find presoaking very necessary. my arista film has a green antihalation coating on the back that is water soluable. i like to give a 3 min presoak which gets all the coating off before i go into my dev. i normally get 6 sheets per dev batch, if i dont wash, ill only get 4 sheets.
berger 400 data sheet says a presoak is required. follow the instructions for the film manufacture recomendations.
for medium format, none of my films ever need presoaking.
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