Grabbing everything is a good strategy. It took me a while to realize that, sure, I may have 30 pieces of item and there are plenty of that item around, so why bother grabbing it, only to find out it could have saved me some time when I encountered a sidequest where 50 were needed. So, by grabbing everything and just stocking up on it all then the later sidequests I've encountered have been no problem to instantly complete.