I suppose you could, but it would be hard for the review committee to compare it against other 7DRLs
From your title, I envisioned something like this:
- 7DRL participants tell you in advance what graphics they want
- you do the graphics for all of them in 7 says
- the graphics get used in 7DRLs, so that the developers don't need to spend time on them themselves.
A bit like in this competition last year, where artists did graphics for 1 month, then game designers programmed games using them for 1 month.
Could be cool... maybe.