Hello, my wallet (Ledger Nano S) changes the address after every transaction. I know that it is because of security reasons (worse to track, I guess) but I want to have fixed address.
Its not for "security reasons", its for privacy reasons.
You can use your address as often as you want. Just don't use the new receiving address.
But there is not a single advantage of using the same address over and over again. Not one.
If there are multiple transaction incoming to a single address - will it save some block space?
That could be a tiny advantage.
I have my BTC address on the website. It is reused. I know I'm at fault. Convenience beats privacy and security.