Pictured above is a hair stopper, that I am honestly glad I own. Before April of this year, I was having a lot of breakage, partly due to having colored ends. Well, I wanted to monitor the breakage as I figured that most of the breakage occured on wash days.
So I bought a hair stopper. It is a great tool to have as it can help you monitor how much hair you are losing on your wash days. Once you collect the hair on a weekly basis (or however, often you wash you hair), then you can see if there is an increased or decreased number of hair being lost. This is helpful because if there is a problem(increased breakage), then you can immediately try to adjust your regimen to reduce the breakage.
If you are having issues with breakage, I suggest that you determine the cause of breakage and try to nurse your hair back to health, however, you will need a hair stopper to see if there is any progress. Of course you can see if there is progress from doing length checks. The only thing is that you have to wait for a whole month or more to do length checks, and will miss any red flags that could have been dealt with right away , using a hair stopper. With the stopper, you can collect your shed and broken hair right after you wash your hair, and keep them in a Ziploc bag to make your comparisons, from the previous wash to the next one.
I am not an expert. I am just sharing what has worked for me. Hope this helps someone.