When framing new walls while refinishing a basement—especially in an old house—it is important to place studs directly under the existing floor joists above (when practical and possible,) even if they are not spaced 16 inches on center.
The reason for this is that it maximizes the “chase” between stud bay and joist bay which you will need for anything from running wire to HVAC ducting to installing insulation. In some cases you may want to add a chicken-ladder, aka in advanced framing lingo “ladder blocking” or extra studs to catch the ends of drywall sheets to minimize drywall cuts or to T off for intersecting, partition walls.
