I get you now… the way you have described it would make quite a useful feature…
I think dblue’spattern resizer tool will take you most of the way there, with a bit of hacking it could be made to work like you describe.
Actually I think using the pattern resizer is probably the best and most accurate way to do it. If you get your notes looping nicely in a pattern, regardless of how long the pattern is to start with, you can resize it to a more usable length