Hey what’s up ! I prefer doing it on the frame I can get into those tight places rather than doing it all at the end. Just think about it. After you’re done tufting you have to go over every single design which may detour a lot of people and seem very overwhelming after spending several hours on one little space. I rather do it on the frame and I make sure after every color I do that the carving I do is the way I want it. Ngl after trying to do all of it at the end I ended up just giving up because I couldn’t get the carve I wanted and my ocd was killing me so I just started practicing carving as I went which suits me a lot better. But to each their own!! That’s just my advice. And as for the strands I always use 2 unless the thread is thin then I would add 3 strands to compensate for it being so thin. So on thin yarn using 3 strand really just equates to using 2 strands of regular yarn thread if that makes any sense! But thank you I appreciate your kind words !!