Potential downsides to requesting an extension I am curently working on my final year project which has a deadline in 3 weeks. This deadline has already been extended by 1 month from the previous deadline (which would have just passed) for everyone as a mitigation measure for the COVID situation. This was applied automatically and was not something that we had to request.
Now, in addition to this, we have been told that we can individually request 7 day extensions (this applies to all pieces of coursework from all courses, not just final-year projects) and that we should expect these to be granted. Again, due to the current situation, we have been told we won't have to give a reason or proof for requesting them.
My situation is that I still have a considerable amount of work to do on this project (I have written up about half of the number of pages we are recommended to do) and one extra week would definitely help to some extent, but maybe not by much. If I wanted to, I would be able to complete the project by the deadline without having to ask for this extension (by working extra hard for these 3 weeks), so the only help the extension would give me would be to be able to produce slightly better quality work and therefore maybe get a slightly higher mark. I have never asked for an extension in my four years at university so I'm a bit discouraged to have to do so now right at the end.
My question is if the professors who mark my project (which are 2 of them) may have an unconscious bias against &quot;late&quot; submissions (even with a valid extension) and this could result in me losing out in a few marks in the more subjective marking criteria. Of course, this could only happen if the markers know about it in the first place, which would be if either

They start marking the projects submitted by the normal deadline before the extended deadline has passed, or
They wait until all extension-included deadlines have passed before marking any project, but they can see the submission date/time when marking them.

One of the two markers is my project advisor, so he will probably know if I have requested this extra extension because we talk quite regularly about how my project is going (so when the normal deadline approaches, he will ask whether I'm (nearly) finished already).
To be clear, I know that in theory I shouldn't be penalised for requesting and using an extension since that is the purpose of them. I am just curious if the markers will assume that students who request extensions (especially in this case after everyone having already been given one) are weaker students and therefore expect my project to be slightly lower quality.
I suggest that if the university has set a rule that they will follow it properly. To make another assumption or guess is a fool's game.
The downside of not requesting the extension is clear; you don't do as good or complete a job. If you want to game that, then fine, but I wouldn't recommend it.
It is a mistake to guess or assume that people are trying to trick you so that they can, for some conscious or unconscious reason, punish you.

I'll note that they could have set a rule that, for example, you can have an extra week for a 5% grade penalty. But it would have been unethical to not say the last part if that was the intention.