[DogMeat]

I'm going by memory here, so forgive me if I get some small point wrong.

Timelimit determines how long to stay on a particular map. For FFA, TDM and RbDM this is simply one straight thru play for X minutes. For Obj this total is broken down into rounds.

Roundlimit is how long each individual round lasts before restarting the same map. It chops Timelimit up into smaller chunks basically. It only has an effect on any map played in Obj mode.

Obligatory pseudo math example:
timelimit=25
roundlimit=10
Round1: 10 minutes then map restarts
Round2: 10 minutes then map restarts
Round3: 5 minutes then map changes to next map.

So if you have one timelimit and roundlimit setting in your config file, the Obj maps will use that. However for your situation you want long TDM and short Obj timelimits, so for the maps you would modify the SCR's with these custom settings.

Example maplist with only a few SCRs modified:
(tl=timelimit rl=roundlimit)
dm1 - uses config file setting (tl=20) for first run
dm2 - uses previous setting (inherited tl=20)
obj1 - SCR changed to two 5 min rounds (tl=10 rl=2)
dm3 - SCR changed (tl=20)
obj2 - SCR changed to two 5 min rounds (tl=15 rl=5)
dm4 - inherited timelimit 15
obj3 - SCR changed to two 15 minute rounds (tl=30 rl=15)
dm5 - inherited timelimit 20
dm1 - uses inherited timelimit on second run

Since the inheritance can get pretty confusing, I'd simply modify every single maps SCR with a custom timelimit and roundlimit in advance. That way I would never have to worry about the map order, inheritance, etc.