for me, I think it depends. Some dramas can take a long time to film and air soon after but the editing can still be bad. Some dramas can take a few months only to film and a long time to air but the editing is quite a bit better.
The issues i have with Thai lakorns is the really bad writing and production wise, they are quite behind. China's case...when you air a drama 2-3 years after filming, the final product looks outdated when it finally airs. Honestly, I dislike both ways. Both countries need to fix this.