Vipassana and samatha are ultimately the same practice. You can't practice one without the other. The more you proficient you become in one, the more effective the other will be.
I think how samatha can aid in - I'd even say undergirds - vipassana practice is well established specifically in the suttas. This is basically the path that the Buddha used ...
OP: Simultaneous vipassana & samatha - in this version of the question
(Yuga,naddha) Paṭipadā Sutta mention there are 4 types of practitioners:
(1) “insight preceded by calm” - samatha,pubb’angama vipassanā
(2) “calm preceded by insight” - vipassana,pubb’angama samatha
(3) “calm coupled with insight” - samatha,vipassana,yuga.naddha
Can one correctly practice anapanasati when one is very used to
The above has never practiced real vipassana if this question is asked. Brainwashing oneself via Goenka or Mahasai mental gymnastics is not vipassana.
Vipassana is not continuous mental noting. Nor is vipassana enduring pain & trying to see changing pain sensations.