Do you ask yourself this question when you get to a customers house to clear their sewer line? Lets be honest, the answer is no. Most (if not all) plumbers are trained to snake first and ask questions later, how else are we going to see those offsets or bellies in the line?
The issue remains that sewer liners can not be snaked and this installation type (CIPP) is rapidly growing and becoming a very popular alternative to the old fashioned digging method. However the most popular cleaning method has not and will not change in the foreseeable future. Which is where the importance of marking your work comes into play.
As a professional CIPP installer you will be installing the liner, but not servicing the line in the case of a backup. If you leave that work unprotected, you’re leaving yourself unprotected. Some people use stickers and some use a tag and fasten it to the sewer cap. None of these methods ensure that the individual servicing that line will see or notice them. In order to fully protect yourself from unwanted damage to your installation, you must ensure they deliberately ignored your warnings and snaked the line with knowledge of your sewer liner be there.

Marking your work is important, sufficiently marking your work is paramount.