The answer to this question is complicated. BrickLink says selling the used set parted out can yield about twice the money than for the corresponding used set: www.bricklink.com/catalogPOV.a…

BUT, there is significantly more work selling these parts individually to multiple people over a potentially long period of time, and even then you aren't guaranteed to sell every last one of the parts. Selling parted out sets is good as a regular activity, where you constantly replenish your stock which makes the issue of leftover parts moot.

If you are an irregular seller like me, you should consider selling the whole set, at least if you get a sale you are guaranteed to get rid of everything at once.