he will then get a massive memory save and a massive cpu slow down
you need to find the balance in between, as long as all your corridor sections and whatever else dont have 50 multi sub object materials but lets say 20 max or less prefferably then your map will be heavy on mem (tho barely, 1 big mesh = 500 kb * 20 parts = 10 meg..) and light on cpu
when a mesh is drawn its split up in sectors, each different texture is a sector, the more sectors the slower it is, if you copy the same pillar 90 000 times around you will have 10 kb in your memory but 10 000 sectors to draw
if youre going to pre render then all your lightmaps do might be a problem for the memory
its also rather hard to get the exact same lighting you had in max in ued
it always shows up different in game then it looked on the max renders
its also very hard to really light everything, you might skip smaller details and if you do then you end up with 2 types of light in game
pre rendered and ued made, with prolly a whole other brightness, result=its looks like a mess
so in short, its perfectly possible to make the whole thing in max but only if the map is medium poly
high poly will prolly kill it, less optimal
and you definalty want to split the whole thing up in lots of different parts
you really want to consider using re usable parts, modular pieces
and you also really want to consider of using a lot of UED's vertexlight
believe me, i tried to do the same as you and its really hard to get it all perfect and certainly in the beginning