When I go hiking, I sometimes have to go off trails to reach some paths that are not yet mapped.
My dilemma is: is it better to upload a trace with some off trail parts, or no trace at all?
That situation can occur when the trail visibility is bad and I have to look around for it.
Another reason is that I can’t find the starting point of a trail and go off trail trough the forest until I reach the trail.
When you upload a trace, you can choose to upload it with various levels of “visibility” - from “private” (only you can see it) through to full identifiable. If you’re worried that your trace might confuse people you can choose “private”, and then only you will see it - it won’t appear to other people in editors or in the GPS traces layer, so they can’t be confused by it. You can also not upload your trace at all, and still drag and drop it over the iD editor.
It’s up to you - you can upload it if you think it might be useful to people, or not if it might confuse.
A little more effort than Andy Townsend’s answer, but GPX files can be edited before upload. If nothing else with a simple text editor as they are just XML files. You could remove the tracks from your exploratory probing and just upload the portions that are on the trails you end up adding to OSM. If made public that would help future mappers.
I sometimes forget to turn off tracking when I am mapping trails and end up having an automobile trip to my house included. A simple edit allows me to remove the non-hiking portion of the track before uploading.