Suppose a multiclassed elf thief/wizard reaches max level in thief (14th, 880,000xp), but can still advance pretty far as wizard (with 880,000 she is a 12th-level wizard, and has still 5 more levels up to the 17th-level cap at 2,625,000xp).
Does she still need to split the earned exp in half (still counting rogue individual awards), or can she devote all exp (not counting the rogue individual awards anymore) to wizard?
DM has already ruled the cap is a hard one (and still allows for bonus cap for high stats, already factored above). No slow advancement, no wishing for allowing to progress in level.