The OP did not ask what is the skimpiest code requirement for some lazy tightwad to adhere to, he asked....what do you do?
And in an unknowable scenario, that's how I do it - 180va per receptacle for general use. Typically I put 8-10 receptacles on a 15amp circuit.
I generally take the use of the area into consideration, and even in non dwellings I may do this but do need to watch out for the inspector that may get hung on the 180VA per outlet.
Take a typical bedroom - what is normally there for load? Outside of an older home with poor heating system or no central cooling often you never see more then 3-5 amps of load for the entire room, or if there is more load then that it is for fairly short duration, like the occasional vacuum cleaner for a few minutes.
Doesn't matter if you have absolute code minimum of one outlet ever 12 feet or wall or if you have one outlet every two feet - the load for the room is still the same, they will just use more extension cords/power strips/triple taps/etc. in the room with less outlets.
I often run 15 amp circuits for the lighting (to multiple rooms) and 20 amp circuits to the receptacles (to multiple rooms). For the lighting I generally try to go by the VA of the intended luminaires, maybe allow some wiggle room for unknowns or future, and in more recent years you can get away with even more outlets as the incandescent lamp is vanishing for more efficient replacements. The receptacles - I have often put 3 or 4 bedrooms on one 20 amp circuit regardless of how many receptacle outlets may be installed - never have any call backs for overloaded circuits.