FACEIT splits its Elo into ten levels: Level 1 covers 100 to 500 Elo, Level 2 501 to 750, Level 3 751 to 900, Level 4 901 to 1050 and Level 5 1051 to 1200. Above that come Level 6 at 1201 to 1350, Level 7 at 1351 to 1530, Level 8 at 1531 to 1750 and Level 9 at 1751 to 2000, while Level 10 starts at 2001 and has no ceiling. The middle levels are only 150 Elo wide, so a short run of wins there often shows up as a new level badge next to your name.
A streak matters more than scattered wins, because every loss in between cancels part of the progress. A booster who wins five matches in a row usually moves an account further than a player who goes five wins and four losses over the same evening, even though the number of wins is identical. That is the practical value of a win boost: a clean run of results that turns into Elo instead of evening out.
The top of the ladder works differently. Level 10 has no upper limit, and the Challenger badge is not an eleventh level but a live ranking of the top 1,000 Level 10 players in each region, so it can be gained and lost as other players move. For accounts already at Level 10, wins are about climbing further within that open range; for everyone below it, wins are the most direct route to the next badge.