So here is my recommendation, nothing groundbreaking but it's how I manage my glimmer in destiny. I earn and spend as needed to keep myself from going up to or over the glimmer cap then I also save all of the items I can turn into the cryptarch for 200 glimmer each eg silken codex, that's my bank roll/savings account which i keep in my vault. If im upgrading a ton of stuff and I need to go over the glimmer cap then I use my bank roll to top off my glimmer. At any one time I keep roughly 200-300 silken codex in vault which means I have like 50-60k glimmer available instead of 25k.