Boss enrage explained — and how do you play around it?

PSA for anyone who has melted to a boss at 25% HP and wondered what happened: bosses enrage when their health drops below roughly 30%. The last third of the fight is significantly more dangerous than the first two — and it arrives exactly when most players are lowest on cooldowns and greediest for the kill. Two schools of thought so far: the burst school (save your damage cooldowns for sub-30% and end the enrage window fast) and the patience school (back off, reset, and poke it down with projectiles). Which do you run — and does the answer change for golden variants, where everything already hits twice as hard?