This is a bit inaccurate. You didn't include the win streaks which means in higher win rate, you get 40 per win rather than 20.
So assuming in 10 games, at 70% win rate, you lose every 3 games, then you get +20, +20, +40, -20, +20, +20, +40, -20, +20, -20 = 120 rating every 10 games OR at best
+20, +20, +40, +40, +40, +40, +40, -20, -20, -20 = 180 rating every 10 games.
While on 95% rating,
+20, +20, +40, +40, +40, +40, +40, +40, +40 -20 = 320 rating every 10 games.
So, to get 5000 rating from 0 rating,
at 75% win rate, you need 278 games.
at 95% win rate, you need 156 games (still higher since this is calculated at 90% based on the example above)
TLDR: Higher win rate is still better than more battles.
There won't be winstreaks in champion league.
Just to clarify, the computation I did was applicable from ratings 0-3999, technically except champion, that's why I said it was inaccurate. Your example above is also the same... Unless you're specifically talking about champion league.
No win streaks in Champion doesn't really affect me - since I'd need to win more than two games in a row and that is rare :D