Web proxy - fuzzing with Burp Suite - should it be taking this long?

I’m running through the small.txt list of possible web page names, fuzzing in the admin/ directory of the target. I have added the suffix .html to the list items using the Intruder settings. Burp has been running for nearly an hour, I am 389 items into the search, the target will time out in 15 minutes and I have only gotten 404 responses to my fuzzing so far.
Am I doing something wrong here? The list is rather long given I am using the community edition of Burp which is slow and the target doesn’t stay online forever. There wasn’t a shorter list I could see so I assume I am using the correct list?

Can anyone help?

I’ve rebooted the target and I’m rerunning with “common.txt”, the list used in the tutorial that is even longer, but still only 404 after 40 minutes and 386 names tried.

Am I missing something obvious?