Generally one doesn't need find explicitly at all; just use the logical addressing vector returned by the logical test.
Alternatives for something like the above would quite possibly be findgroups and splitapply depending upon just what is to be done next.
Or, of course, there are all the binning functions such as discretize that might come into play.
Without the end use here, it's hard to say specifically.
One note, however, is that creating sequentially-numbered variables such as above is generally a sign that the code factorization is not optimal in MATLAB -- arrays or cell arrays would be far better in all likelihood. Once you've created such a set of variables, you've made using them difficult for anything other than just duplicating the same code over and over...