During both the "High Reliability Hand Soldering" course I attended back in the day, we were expressly warned against re flowing faulty joints.
The rule was:- Desolder & remake the joints,
I know that re flowing is fairly common with SMD boards, but it was definitely regarded as a "no-no" for "through hole"components, probably due to the less than ideal contact area available with such devices.
Most things are good, in a perfect world. And BOY am I not perfect !!
Sometimes, we are limited to what we have at hand. (I don't have specialized 're-flow' equipment).
Visible Surface-Mount chip pins are one thing. When there are hundreds of solder-pads underneath
a complex chip, then my only option is/was Archaic methods!! haha...
6-8 years ago, I, (and numerous others globally!), there was a common fault with the Video Chip in
HP Laptops. I 'repaired' probably 15 to 20 of them, using the kitchen oven.
Stripped down to bare main PCB, I placed them on top of Socket-Set 'Sockets, with other heavy metal
'sockets' sitting on top of the problematic 'chips', and baked in the oven for 15 mins.
ALL of them came back to life....