I come from a D&D background; I haven't seen anything in the books regarding the concept of taking 20. (taking 20 basically assumes that you will eventually succeed at a task that you try at for long enough, failing numerous times before you get it right)
I don't think taking 20 should apply to skill checks as it tends to defeat the narrative aspect of the dice, but there are some scenarios with force powers where it would definitely make sense.
I have a Sentinel with maxed force leap... Now lets say he wants to jump up to the roof of a building; perhaps a few medium jumps or a lot of short jumps as he leaps up from balcony to balcony. There are no time constraints and no setbacks. Now if I had to roll for every jump I would just keep rolling the force die looking for white pips... That doesn't make sense to me. If you can take all the time you want and there is nothing interfering then wouldn't you assume he took his time with the task, only harnessing the light side of the force, and successfully leaped up the building. That's basically taking 20 for force leap right? Now if you introduce setbacks then you cannot take 20. Lets say I wanted to jump up the same building, but during a hurricane. Now I would probably have to roll Athletics or Coordination after every leap to see if I was able to stay on the balcony I just leaped to... And if I opted not to spend a dark pip I would have to make another check to see if I could brace myself against the storm as I waited to channel the light side of the force.
Another scenario: with my force rating of 1, I need to roll 2 pips in order to jump medium range over a precipice. I could keep rolling and rolling the force dice until getting 2 light pips, then I jump - but again; I don't think I should just keep rolling a dice waiting for 1 particular result... We would assume I just mediated and channelled the force until I got the 2 pips I need and then jumped. Again, inversely, if I was under duress I'd be rolling other skill checks as well and couldn't take 20.
With sense thoughts lets say I sat down at a bar and tried to read the bartender's thoughts - assuming he doesn't go anywhere I would just sit at the bar channelling the force until I read his thoughts... This one could get a little weird though... Force and destiny does not mention rolling discipline checks when doing certain force powers but the other books do... Would I only roll if the bartender was force sensitive? Otherwise would I take 20 and assume I could read his thoughts? Again, only if there are no skill checks or set backs.
Same again for force heal - wouldn't I assume that with enough time I could channel enough force to heal?
As far as I can tell the only time you should have to roll a force power check was if you were rolling against another force sensitive, if you had to combine the force power check with another check, or there were time constraints... Any other time you would just assume you spent time to channel enough light side force power.