Since a fly fishing vest is nothing more than a piece of clothing designed to hold all the little stuff inherent in the sport of fly fishing, it's not particularly surprising that a good fly fishing vest should have quite a few pockets to hold it all.
Another drawback of having too many pockets on a fly fishing vest is that you will soon find stuff to put in them. What's bad about that, you ask? Well, as any backpacker can tell you, the more space you have in your pack, the more you bring—even if it isn’t needed. As such, a fly fishing vest that a multitude of pockets will quickly weigh a ton, creating fatigue, discomfort and is destined to become an organizational nightmare.
To begin, let’s start with what a fly fishing vest actually does. Basically, a fly fishing vest is what holds all those myriad of streamside fly fishing things. Those things the fly fishing vest holds range from clippers, flies, leaders, tippets, various tools, line cleaners, fly floatants, weights and frequently a bewildering array of other little things.
So, how many pockets should you get on a fly fishing vest? Well, while it's open to debate, I suggest somewhere between 10-20 pockets, give or take a few. This number of pockets will be plenty—probably more than plenty—to hold everything needed without going overboard and creating hopeless disorganization in the vest.