A single leather sole is around 6mm including the welt and it's not always easy to get a consistent finish.
Top view of toe
I remember taking 5-6 hours for one side when I first started out. Nowadays I'm down to slightly over an hour and half. Good improvement but still some room to get faster.
I do all my outsole stitching by hand and usually at 11spi for a single leather sole. For comparison, the higher end goodyear welted shoes usually come in at 8-9 spi and is done by machine.
Stitching to be hidden away by a thin flap of leather
Based on 11spi, there's about 150 or so stitches in the forepart of the shoes. Stitching along the beveled waist will be hidden and it's not necessary for a high spi as pictured above.
More photos below.
Ramie Thread from Japan