I don't shut down my M1 Mini unless I have a specific reason.
I have no deeper technical understanding around this, but I like to think of it this way:
After a restart, memory is 'empty'. As you launch applications, open documents, visit web pages etc, the memory fills up with data for faster access if it's needed again, i.e better performance. If you have plenty of memory, it will mean more for the performance, if you have less, it will mean less, but still improve performance. Todays macOS'es are pretty fantastic at managing memory.
After a restart, it takes time to build up the fast access memory again.