Can a wire gauge be too large?

I am far from being a electrician but I have increased the wire gage when rewiring
some cars that's harness was a mess from age, burns and previous splice ins. Mostly just to use up what wire I had available at the time. I jumped up a couple sizes with out any problems at all.
Built a new complete harness front to back using the schematic in the factory service manual.
Put a fresh battery in and a car that has been dead since the 70s all came to life. I cleaned a lot
of contacts and changed bulbs while I went thru the job.
If there is a down side to what I did it was all the wire was the same color due to me working with one roll. So trouble shooting will be more difficult now.
Of course the battery and starter cables were built larger and not from the same spool.
Did a e-body, 56 desoto, and a couple trucks like this. The wire was good quality belden
that was donated from a factory my uncle was employed at. Soldered all terminals.
If there is a reason not to do it this way it has never shown up for me.