[{quoted}](name=AR URF,realm=NA,application-id=3ErqAdtq,discussion-id=9FcnUKEN,comment-id=0000000000000000,timestamp=2018-01-22T18:37:24.329+0000)
But 4v5 is almost never going to end well. Especially if the ADC is the one split pushing.
FIrst, you keep moving the goalposts. "But if this is about to happen, but if the adc is the one split pushing". Obviously there will always be extreme cases where splitting is a bad idea. There are also cases where teamfighting is a bad idea EVEN if the enemy team is pushing for your inhibitor. If you're very behind letting the inhibitor fall can help you get farm to catch up since the wave will automatically push into your base (plus they're worth more gold per wave as each wave has a big minion).
Teamfighting with an inferior comp is also almost never going to end well. If you see your team pick champs like Trynd or Udyr the best thing you can do is pick a champ with high wave clear and area denial. Ziggs, Anivia and Xerath are great examples of this. These champs can easily defend a tower against multiple people for much longer than most champs (or at least until the enemy takes baron and / or gets banner of command). While you're defending your lanes the splitpushers can take towers and in the end you get a net benefit from it. I've won countless games by picking Anivia and just killing minions while the Nasus on my team destroys towers. In the end the enemy team is forced to back and my team is allowed to begin regaining the map.
Learning how to play the map like this (it's called macro play) is one of the big differences between lower elo and higher elo games.