That's a pretty good question, but the answer is not so clear-cut until you have an actual model in the air with whatever its CG, trim and mix happen to be, plus of course roll-rate and airspeed.

I will say that my half-rolls (1 of 2 from upright to inverted or inverted to upright) I find I just about always help the roll around with a nudge of top rudder. This has become pretty much automatic for me, and I never think about it when doing it.

I was coached in my early pattern days to do linked rolls, as many as I could string together, holding constant aileron all the way, and keeping on axis using just elevator pull at upright and push at inverted, nothing with the rudder. If I had tried to sneak in top rudder at the 1/4 and 3/4 points that would have made it impossible for me to practice. I had enough trouble just getting the elevator timing right, and two axial linked rolls was a great achievement for me, and three was a miracle.

When I was practicing linked rolls, I felt I could get better timing by slowing down the roll rate, and that worked for me. Pretty soon I actually found it easier to do a slow roll on tight axis than to do a regular roll. But for contests I always practiced with higher airspeed and faster roll rate, so I could just breeze through a roll with nothing but aileron and take whatever points I could get. But as time went along, I became dissatisfied with fast roll rates, and felt a slower roll was more graceful.

Even my coach admitted that when he practiced linked rolls, the guys at the field would compliment him on his rolling circles. He told me that what they didn't understand was that he was trying to roll in a straight line, but when his concentration slipped, it was easier to link rolls in a big circle than it was to roll in a straight line. I'll testify to that myself.

One exercise that will help your understanding of inputs at the 1/8 points is to fly the length of the field on a straight track, wind-corrected if necessary, on axis. I believe you'll find that some input from both rudder and elevator are needed to hold a steady, axial track with your wings steady at the 1/8, 3/8, etc. points. Consider that a V-tailed model can be a substitute for a conventional tailed model at the 1/8 points. What the V-tailed model has mixed in the linkage or TX, you have to mix with your fingers to get the same result.

When you've absorbed that, then try an eight point roll covering the length of the field, left to right then right to left. When you can do that reasonably well, let me know and I'll buy the beer.

Not too long ago on a related thread, someone quoted his old pattern coach as saying 'All rolls are slow rolls,' meaning rudder and elevator inputs on any roll. I think that's probably good advice, but it must be practiced, and the plane must be well set up and trimmed and mixed, all of which is a lengthy process involving many hours at the field.

My final word, if you are trying to learn precision aerobatics, is to learn whatever maneuver by slap dashing any rough approximation of it that you can to start off, and then work on little aspects of it one by one until you get them worked out. This takes more than one day at the field, and takes some thinking and maybe sketching at night, then practice, reflection, clear intent at every practice session.