I'm using a couple of machines, Mac, Ubuntu, and Raspberry Pis and all of them have at least 3 aliases. In addition, basically, I use zsh since I love oh-my-zsh.

If you are not familiar with alias, this post will be useful.
https://wpshout.com/quick-guides/make-bash-alias/

My .zshrc/.bashrc have followings.

reload

Sometimes I change settings, but I don't want to type source blah blah blah.

alias reload="source ~/.zshrc"

h

I use this heavily, especially to check ssh destination lol

alias h="history"

cl

Love to keep my iTerm screen clean as much as possible

alias cl="clear"

p

Sometimes I do typo like pyhton or pythoo, so this is to run my python scripts smoothly.

alias p="python"

I also put aliases for my python virtual env since I'm lazy.
For Ubuntu and Raspberry Pis have open which Mac uses.