First tower falls in 10min, every other in 20, after that its just survival game in your own base.
EDIT: Yes, i understand that match history and statistics say that games last longer, but lets be real here, the outcome is decided in 10-15 min, everything beyond that point is (mostly) a waste of time.
Games last from 28 to 31 minutes. In your region it goes from 29 to 32 https://www.leagueofgraphs.com/es/rankings/game-durations
What scaling champ? Almost ever scaling champ spikes mid game
First tower falls in 10min, every other in 20, after that its just survival game in your own base.
Doesn't matter if scaling champs exist when ADC's are ramping up in damage by 1-2 items already and most champions in the game that aren't tanks have enough burst to 2-3 shot most non-tanks.
Scaling champs have lost their point when early and mid game champs do enough obscene damage to get kills even in late game. Only good remaining scaling champs are Cassio, Vladimir, Yi, and Kassadin.
Short answer is: they don't.
Seldomly games do get long enough to scale, but so far, in both S9 and for most of S10 my games end at around 20 minutes due to FF or by 25 minutes if we don't. About 1/10 go beyond 30.
You can see most champions that used to scale build new things that emphasize early games. For example, Cassio takes Conq to get huge AP and healing. Anivia opts out of mana items (or only buys one) since she takes too long otherwise. Kassadin takes PoM to activate his max-mana ulti plays as early as level 11.
Other traditionally scaling champions, like Ziggs just suffer. There isn't much they can do, since champions achieve lethal status far earlier than he does. His AoE damage and turret-taking capability is also just not fast enough to matter much and his winrate suffers. Either Riot lets them drown or they must buff them as we can see them buffing Ziggs next patch in 10.2. You can see this with Kayle and moving her power breakpoints to earlier Lvl 6 and 11 since rarely does she even get to 16.
Unfortunately, even when games do get to 30m+ its typically better to have had impact in the early game as a scaling champion to have secured dragons and rifts than waiting. The truth of the matter is even if you played a champion that straight up had an ability to destroy the nexus if the game hit 35m, you would still lose most (only 46% winrate) of your games if you're playing to try to stall or reach that point.
Supporting Evidence: S10 games that end 30m or less: 54% *most fast-paced games S9 games that end 30m or less: 52% S8 games the end 30m or less: 50% S7 games the end 30m or less: 37% *slowest paced games *had games that could regularly last 60m+ S6 games that end 30m or less: 46% *had games that could regularly last 60m+
+Another interesting fact: Games in season 10 end 8% of the time at 20m, where only 1% of games ever ended at 20m in S7 (the slowest season). This implies, that games not only don't last nearly as long as before, that also a pretty heft amount of games are decided almost entirely by laning phase alone, which greatly favors hyper-aggro and base-damage champions/mechanics.
Can people stop with argueing the 1%...
ok, so Iron or bronze may get longer games... that still leaves 80% of the game elo's having champs that scale in an environment where they can't.
That's the whole point of the topic, not nit picking the bottom 2 elo's to make a point while ignoring the rest..
Scaling champs need a rework if this is how League is going to be.
Also remove infinite scaling...
LOL you can hit lvl 18 pretty fast. The game is in a GREAT state atm, one of the best in years. lots of my friends are using "scaling champions" like GP and are doing awesome in the climb. maybe just get better?
if almost every game ends in 20min?
Stop surrendering so early maybe.
As a Kayle/Fiora main, I only play for those games where my team doesn't run it the fuck down. The worst the game can be for a late game champion is one lane winning, one even and one losing. Anything worse that that it's best to ff and move on.
Isnt that Why every lategame champ early game got power creeped in last 2 seasons Just bc late game now is 20 - 25 mn 
... and Its What causing this insane high in game .
Defensive options are so bad in this game. Such that the only boring option is to always go on the offensive and be aggressive.
Yawns.
They said that aggressive games are more fun to watch. I, on the other hand, find that it's boring when it's the only option or style of play - To punish on all corners of the map.
Riot showed statistics about this stuff in 2018.
Games are decided at minute 10 clearly, and the chances of making a comeback are a ridiculous 4%.
Nor surrendering at 15 minutes when your team is losing is literally a dumb waste of time mathematically speaking.
Not to mention that playing "late game champions" basically means you want to lose the game at this point.
