Evaluate the situation.
Stuff to weigh (+ means go in, - means piss off):
+ the enemy is low
+ early in the game
+ you have an execute (lee sin q, elise q, nidalee q, etc.)
+ your team is alive/outnumber the enemy
+ 5th dragon for either side
- late in the game
- lack of execute against an execute
- last man standing
- 2nd or 4th dragon
- you have buffs
That's a really cool video of bugs that were supposed to get removed a long time ago.
Try it yourself. It isn't intended to work like that. Google it, there's multiple redposts from the old forums confirming it.
Grats. Did my placements, ended up 4-6, and ultimately got fucked over and placed in B4. Reached Promos once, lost 'em 1-2. Bronze feels pretty bad, not gonna lie. Haven't found many bots or scripters though, mostly just uncooperative players that end up dragging the team to hell with 'em.