While there is nothing wrong with it, it is not preferable...
The preferred method would be to make a kolata.tce which contains the static system files and add it to your tce directory.
there's no question that your way is more ideal, it's not only faster, it is more likely to keep your tc setup working in the long run.
the ideal way would be "preferable" too, if it was not easier (more friendly) to add a line to filetool.lst than it was to create a .tce. creating a .tce is not the most complicated task, but i find myself putting off doing it this way, even though it was the way i originally planned to do everything (avoid filetool.lst completely!) but it turned out to be extremely friendly!
if there was ever a handy tool for making .tce's by simply giving it the name of a folder to "zip up," where the folder contained the proper structure (like the source directory for a dsl remaster does) then i think more people would do things the ideal way. the thing about adding to filetool.lst is, you don't even have to think about what you're doing so much. one line of text, there you go, it's added now. (but it's not ideal, just easy.)