Does playing HU table really help at FT or late in Sng?

I have had people tell me in the past that playing at HU table or HU SnG will help me improve my late stages tourney play and HU at the end of MTT or 9 seat Sngs.

I really didn't think it was that useful for me. I always feel that the play that leads up to HU can have more impact on the HU play at the end. While there are aspects of straight HU play that can help, I've always felt player play observations more useful.

Not really, because 100bb deep HU is nothing like 10bb deep HU.
You can play HU sng's

sng's are also not at all the same as a FT because of the payout structure and stack sizes at the start of the sng.

Your best bet are probably 30-50 man multi-table sng's where you get to a lot of final tables that are very similar to big field final tables.

HU SnGs helped me a lot with my lategame play when I was an SNG grinder. HU cash wont translate as well.

playing HU will improve your poker in general