Life’s too short for filing email into folders.
Conversely, plenty of people find separating emails out can reduce the time spent searching later.
It doesn’t take long to run a few finds and add labels (if it’s gmail) or drag them into a folder. In gmail I have filters set to up so that many of them get labels assigned before I even see them.
If you had 39,676 letters from banks, utility companies, council, insurance companies etc etc would you put them all randomly in a single huge drawer? I wouldn’t and that’s the principle I apply to emails – if a small up-front effort filing reduces the time and effort spent identifying them later then it’s a worthwhile step in my book.