Gordon Shumway said
If you constantly rotate the rosin, you won't wear a groove in it.

  

Yeah, I know, I say with a sigh! I keep forgetting. Have been bette about it lately.

@HP, yes, I play a lot lot. Can’t tell by my playing. That rosin is used on my violin, viola and cello bows, although I had to get the Kaplan Premium with Case-Dark from Fiddlershop this Summer because, with my window AC units, I couldn’t keep up as much as I would like with the extremely hot Summer. I was not going to lower the temp desired on the AC units and have them turn on more often, so I changed rosin, This is the first Summer with these instruments, so it might be like this even with the normal Summer temps. That rosin won’t need my vinyl because, like Fiddlerman Rosin, it has its own handy case instead of a cloth wrap. They are different style cases, but cases, none the less. 

But, I do play them a lot. It makes my own little corner of the world and I get involved and lost in it when playing those instruments. If strictly playing time made you better, I would be a virtuoso. Unfortunately, it takes knowledge and an ability that requires training and practice. Time playing is a big part, it is the other things that give me issues.

I cut the vinyl down a little if the vinyl channel that is parallel with the bow when I hold it rubs the bow hair. It is as short as I will make it. It isn’t going to hit the bow hair any more. Since I learned to rotate, I am not getting grooves on other rosins. It is easy enough with the vinyl holder, I just hold it in a different place. The vinyl is grippy, even though it looks slippery with the shine, so it does not even try to fall out of my hands.

@bob, if you don’t even sew with a needle and thread, you can do this without the attached ribbon. It makes it easier to pull out of the rosin case. I cut the original cloth wrap off around the bottom to have something to glue the lining side of the vinyl to. But, the gluing is not necessary, either. Like the ribbon, keeps it all in place. If rosin was used up quickly, I wouldn’t have bothered actually affixing it to the cake, but one cake lasts a long time.