Just let me be clear here, I'm not trying to convert anyone from their tried-and-true practices. I particularly try to not piss off guys with black hoods and sharp axes. But I would like to point out that as we get older, we may get wiser but our fast twitch muscles just suck. This translates into slower reaction times than we were used to.
I use pulleys for slack tending now on most everything. I have not had much problem getting a Blake's or Distil to advance. Both being four coil friction hitches, I would have to believe the Tautline and Prussik would advance just as well. I think the problem some might be having is that just as in footlocking or hip thrusting, when you are advancing the hitch it has to be loose. When you sit back and put your weight on it, you lock it up. In order to continue your ascent requires unsetting (loosening) the knot so it will slide easily.
And, Butch, you are right; there is no way your hitch is going to self-tend. But if you tied it a little further away from you and kept it loose, you should be able to get it to self-advance while you pull with both hands from below and the only difference between that and what you are doing now, is that if things go to hell, you are tied in and ready to come down at a moment's notice.
Dave