I have used a similar approach when working up loads for my CF rifles.

If you have a way to pre measure your powder, tubes or film canisters, measure out your loads before going to the range. That way you can measure the 3 or 5 shots of powder before changing the measure and thus have the most consistency for each powder level. Then put up as many aiming dots as you have powder levels and shoot each powder load at a different dot, i.e. one dot for 70gr, one for 80gr, one for 90gr, etc. Shoot one of each and then go back and start again. This does help in weeding out some differences over time that can occur as the day goes on. Keep everything else as consistent as possible for best results. I would also suggest doing at least 2 or 3 range sessions like this to average out the results and check for consistency of results. This helps justify and gives a good reason for more range sessions, right?

Good luck and keep us posted on your results.