For example, is it really necessary to clean the ducts, sweep the chimney, add insulation, repaint the house numbers on the curb, etc.?

If you'd like to purchase a slightly rusted, repainted, brown awning, I'd gladly post an add over in the marketplace where we can discuss making a fair deal on it.  ;-)I think I'll be able to pop one of the panes out for replacement.  

The house was gross, barely repainted, with 70’s carpet.

Right now, I'm seriously considering going through and repainting the entire place a platinum white. 

New carpet/flooring, repaint everything including the kitchen and bathroom cabinets, remove any wallpaper and replace drapes worked on my house that had heavy cigarette odor and yellowing.

A handyman might be great for fixing a leaky faucet, but when it comes to turning a unit, you need to coordinate multiple teams to repaint, clean, carpet, etc.  

Re paint it , add some trim , add some shutters .

Also, after the popcorn stuff is gone, how long should one wait before repainting?

For example, there is no incentive to do a fast and quick touch up paint over charging for repainting an entire room -- in fact this may not even be possible if no one kept records of the brand/color and finish of the original paint.   

We repainted entire house.