It depends a lot on where you're iterating. If you're iterating concepts and structure, sketches work perfectly. If you're iterating the size of a shadow, the exact color pallet, the exact shape of a logo then you'd better be in Photoshop.
For all 37s likes to talk about not using Photoshop they don't have pixel-perfect design at all and yet still had somebody slaving over Adobe products while putting those logos together.
For all 37s likes to talk about not using Photoshop they don't have pixel-perfect design at all and yet still had somebody slaving over Adobe products while putting those logos together.