Whatever works best for the particular situation.

I've been working on a related case for the past 2 weeks.
Background: 2016 flood affected a slat-back oak chair dining set. Dr. owner had a patient do the repairs, refinishing. The patient, I think, didn't know what all to do, what to do properly and/or should be done. Seems the chair seats had warped and started coming apart... several boards per seat.. Chair frames had come apart to some extent, also. Since flood damaged, don't have to worry about messing up a finish.... heat gun use.

The guy tried to glue the boards back together without cleaning the edges or jointing them square, to mate properly. Lots of mold and mildew still on the board's edges. He ended up with gaps between the boards, then tried a white-ish filler to fill the gaps (on brown boards). *Subsequent stain on the chairs is Old Masters Provincial stain.

Beyond that, he seemed to not clean the stretchers for re-gluing into the legs. He shot wire nails in some, for further securing. He shot wire nails in some of the backrest slats, as well. I haven't/won't attempt to remove these nails.

I separated the seat boards using a heat gun. I worked the heat along the whole length and the boards slowly separated. Took about a hour each seat. On all 4 seats there were some glue lines that I sawed through, rather than using the heat gun. I flattened any major warping, then jointed the edges clean and square before gluing. Also added a strip of white oak to make up for removed seat width, from jointing and sawing.

Yesterday evening I put the first coat of finish on. 9 pics, scroll right.
https://www.flickr.com/photos/438361...in/photostream

Sonny