Single R-gachas are certainly an attractive option. It gets iffy whether they are worth it since your probability of getting a limited SR can be higher if you actually spin the R-gacha than by feeding it to Kurito, but we also have very little solid knowledge of relative drop rates for higher tiers.
Hypothetically speaking, would you be willing to spend 5 R-Gachas if you knew that it increased the drop rate by ten times? The wiki tells us what you can get from every combined point value, but we don't know what the drop rate for items at that level. I assumed that if you got to 10,500 points, (there are only three rewards listed for that) that you would have roughly 1 in 3 odds. I never considered the fact that despite having only three possible items as rewards that the percentages could be something like:
SR Card: 10%
Pero Pudding x 2: 15%
Card Reveal x 2: 40%
Card Reveal x 2 + Pero Pudding x 2: 35%
Those numbers are COMPLETELY fabricated, but they illustrate my point. I did two Kurito attempts for 10,500 points each and got CR x 2 + Pero Pudding x 2 +/- 50 candies both times. If I could afford to do a bunch of 10,500 point offerings, I'd love to see if I get something else. Otherwise, we don't really know if the odds for each reward are roughly equivalent or if some rewards are more heavily weighted than others.
Experience at the 1 R-Gacha level indicates that the rewards are not evenly divided among the possibilities. More often than not, an offering of an R-Gacha ticket yields a SR3 +/- (more often plus than minus) an R Wild +/- some number of candies. I've gotten only an SR3 and nothing else, but ~75% of my R-gacha offerings yield SR3 + R Wild with or without candies.
Are other people getting a similar rate of return?