Shortcut keys save you time. But, they are hard to learn, and we are so used to reaching for the mouse, that it is a hard habit to break.
I recommend learning one shortcut key at a time.
And, I also recommend using a shortcut key if you have something that you are going to do a lot, even if you are not going to do that thing again for a while, and you will forgot the shortcut key, but for that one off time you are doing that thing, it is worth using the shortcut keys.
For example, I was doing some work for a client and needed to add to print area multiple times and insert a couple of page breaks on about 10 sheets.
It was worth checking if those had dedicated shortcut keys – they did not. BUT everything on the menu can be accessed with the keyboard and this is still faster than using the mouse.
ALT key activates the key tips which are letters in small labels over the menu. Then as you get used to it, you don’t even need to look anymore and can just do it. Now, I probably won’t remember that ALT, P, B, I are the keys for Page Layout, Page Breaks, Insert, but it doesn’t matter as it was faster than the mouse for that job.
So, next time you need to repeat an action multiple times, check for shortcut keys or reach for the Alt key!