Good Old Time Machine Editor - A Useful Free Utility
By default, the built-in macOS backup utility, Time Machine, makes
a new snapshot on your designated backup disk once an hour. This can be
problematic during your work day if you need the full system resources
of your computer, but it has decided to start copying a bunch of files
to your backup. The venerable utility, Time Machine Editor, a free app
by developer Thomas Clement is the solution to this problem. To use TME,
you first need to go into Time Machine options in System Settings and
set your backups to "Manually." Download and install TME from the developers's
website or through Homebrew.
brew install --cask timemachineeditor
Once installed, you can choose any of several options to schedule Time Machine backups. On my work iMac, I chose to stop the backups between 8am and 5pm when I am using the computer but to continue hourly backups after that. To be on the safe side, TME allows you to create local disk snapshots during the time you are not writing to your backup disk. They are very fast to make, and provide additional restoration points. Since they are local, they do not protect against a disk crash but can be useful if the machine goes away from the backup disk for a while.
I've used this utility for more than a decade, and it's never let me down.