The problem is, no matter how explicit the guild rules may be or how much encouragement officers give out, I can't ever seem to rationalize taking anything out of the guild bank. I've accepted new bags a time or two, but I can't seem to bring myself to take anything more.
The looser the guidelines, the more I balk. "Why is all this stuff in here, anyway? Am I the only person in Azeroth who doesn't have a bank full of this stuff already? What if I only took this one pair of boots? Is that too much? Maybe I'll just take this humble little stack of wool to get over the hump in first aid -- but there's not much here, so maybe it's for something more important?" Trying to decide how much is too much is utterly agonizing. Even with clear guidelines in place ("Take anything you need from the leveling gear on tab 2 any time you can use it"), I become completely mired in not wanting to make a pig of myself.
My usual pattern is to peek into the vault once or twice when I'm in my high 20s or 30s, panic at the prospect of making a withdrawal, and then do nothing but deposit odd drops and crafting mats until I'm in my late 70s. At that point, gear has usually become so specialized that there's rarely anything helpful just sitting in the bank and waiting, and if there is, it's too "big" for me to feel justified taking it. It's like that one cooldown you never use because you're saving it for A Very Big Emergency -- you know you're wasting it by not using it, but you just can't bring yourself to press that button ...
Do your guildmates freely share items and make frequent use of your guild bank? Does your guild have clear guidelines about what members can put in and take out of the bank? What's the biggest thing you've ever taken from a guild bank? And is anyone else out there paralyzed by not wanting to seem selfish about taking items?