PSA: When the enemy is splitpushing your inhibitors, stop being so aggro for kills.
Just had a game where Lee Sin was constantly going for kills even when the enemy Nasus was at our inhibitor. He kept going in and did get kills, but the enemy team managed to delay him long enough for Nasus to secure the inhibitor. Eventually the Lee sin died and so did the rest of our team except for the support. We ended up trading four for four. We could've just left him to die, but then the enemy would've still delayed us and let Nasus destroy the inhib. I was top lane, so it was my role to stop Nasus, but I had died pretty early on in the teamfight.
Another instance of this happened when we were fighting at Baron. We saw Nasus pushing our bot towers, but Lee Sin, alone, went super ham on the enemy. We had no choice but to follow up. However, because he went super deep and the rest of the team was really far away, it was a ineffective engage. We ended up trading two for two, but Nasus had managed to secure the bottom inhibitor.
So please, when the enemy team is at your gates, and you still have three people alive, just back and defend your base.