Best way to convert all lights on one switch, to one switch per room

I’m about to tackle refinishing some parts of my basement.

When you walk down the stairs, there’s one switch that controls all the lights; I’d like to convert that to one switch per room.

Is it code-ok to run some romex to a switch from the light, leaving them all on the same circuit?

Thanks!

EDIT:

Right, here’s the current floor plan w/wiring.

I was thinking I could:

1. bypass the current switch that controls them all (by tying white and black wires in that box at the base of the stairs; this would save me some time, where I can reuse the wire that currently runs the length of the basement).
2. use the now-hot source to wire a single-pole switch in each room, taking some 14-3 from the existing ceiling boxes down to each switch. (14-3 instead of 14-2 because of the capped-off neutral requirement 2011 NEC). Like so: