I used to do that, even the hidden ones. Clear the entire fucking map. But lately I realised that I do not use 99% of the items I pick up. I never use berrys, never use TMs. Maybe a revive or a potion here and there. Rarely evolution related items. Piss on x-items. It all just sits in my bag and I waste time picking all the crap up. My team is strong enough and it would literally have no effect on it if I didn't pick up most stuff. I'll probably stop.