There is a point in doing it. (By the way, these are network drives, so Everything won't work.)
What I want to do is silently determine whether one particular file exists "somewhere" below \THR\Downloads\ I can accomplish "silently" by having the ffind output>NUL. Then I look at %_ffind_files to determine whether the file was found. If I don't use /F I have to wait for ffind to look through over 700 subfolders, all but 3 of which definitely won't contain files.
There is one folder for the year, 12 subfolders for the months, 1 subfolder in those for each day of the month, and each day subfolder has a \comments subfolder. After a day is processed, its folder is moved elsewhere. So on Jan 1 ffind would have to search 1 + 1 + 12 + 366 + 366 = 746 folders. Since Jan 1 would be near the top of the tree, with /F it stops almost immediately.
(By the way, even with setting /S to only search a specific level, it would still require searching up to 366 "day" folders.)
With /F, there is no way to tell just from looking at %_ffind_files whether ffind found something. %_ffind_files comes back 0 whether ffind found something or not. I would have to write the output of ffind to a temp file, then check whether the temp file has a length greater than 0, then delete the temp file.
For an unrelated issue I already use ffind to check the data file for the "bad" characters ; = < and >. When I found out TCC/LE doesn't set the %_ffind_ variables I had to use the write-to-temp-file-then-check-file-length-then-delete approach. But that workaround shouldn't be necessary with TCC.
Aside from that, the Help doesn't say anything about ffind not setting the %_ffind_ variables if the /F parameter is used. So someone expecting it to work would think their program has a bug elsewhere.