Unlike many tournaments, which usually have an element of elimination, ladder competitions can go on indefinitely.
However, if the balance between number of participants and duration of the competition is defined properly, this usually results in a representative ranking.
In this case, players are moved up and down the ladder according to competitive results, dictated by previously determined rules.
The Ultimate Fighting Championship considers its official rankings (decided by a media pool, based on match results) when matchmaking, though not strictly.
Due to the high incidence of training injuries, unranked or low-ranked replacement fighters often compete higher up the ladder than they otherwise would.
This is also (more rarely, usually on pay-per-view) done for promotional reasons, when a big name or rivalry makes a low-ranked fighter the more marketable option.
Sometimes no similarly-ranked opponents are available, and a fighter may risk losing their spot to a low-ranked one just to stay busy.
Rematches are generally disallowed, excepting some championship bouts and others ending in controversial decisions.