For walls parallel to floor joists, aren’t there some schools of thought that say it isn’t just all that important to have joists under or immediately adjacent the wall plates?
Remember, we are talking about strictly nonbearing interior walls.
I have always put in extra joists, but I am looking through my new JLC book, “Field Guide to Residential Construction . . . A Manual of Best Practice,” and seeing on page 119, simple 2×4 blocking on about 32″ centers, under a wall like this.