zsh-autosuggestions has definitely saved me more than hundreds of hours. When you type part of a command, it auto-suggests previous commands you've executed and then lets you expand to them, cutting down on your typing, on average, 75% or more.

For example, typing "scp" could expand to "scp -r myself@servername /home/myname/.logs/logfile ."

It's a concept that originated with the Fish shell, but is useful if you want to maintain some semblance of bash compatibility.