[Keith]

As others have mentioned I think some of the contestant replacement problems have stemmed from there only being 11 episodes, with just 5 heats and 3 quarter finals. Presumably its the BBC who decide how many episodes to commission, and they may have been erring slightly on the side of caution.

Given that ratings have been a success if recommissioned it'll hopefully get a longer run of 14 or 15 episodes, which would allow for 7/8 heats and 4 quarter finals. With more heats they may potentially be able to film two on the same day, using the same rounds, but not broadcast as subsequent episodes. I suspect this may be why the original 90s series almost always featured The Wall, as the set was permanently in place. They'd probably require a couple additional Gladiators to cope, however I'd assume an extended run would provide a budget increase.

The quarter finals pairings could then be the winners of the heats from the same day, which would mean the contestants would have had at least 3 days rest. Having four quarter finals also means the semi-final can be paired in the order the quarter finals were filmed, to ensure contestants get some rest.

More episodes also gives more contingency in the event of needing to replace or substitute a contestant. For the heats reserve contestants can be used. The for the remaining stages the reserves are the fastest runner-up (or two) from the previous round.