User blog comment:Lancer1289/Are People in Multiplayer Lacking in Intelligence?/@comment-5089947-20120729065837/@comment-3325589-20120729131426

"If there are two or more others down, I'll use it as soon as it's (relatively) safe."

Worthwhile note for newer players here: even if you're in a situation in which reviving yourself with gel is obviously the best option, it can pay to wait 5 seconds or so. This gives time for enemies to disperse a bit so that they don't immediately take you out again, and is especially important if any enemies with instant kill attacks are nearby (Banshee, Phantom, Brute, Atlas). The only thing worse than having to gel back up again immediately after having done so is getting impaled and not having the option.