Yes, clone to a back up drive. I like SuperDuper, but many use CCC. Bootable clones are great for if an upgrade or update "breaks" apps you use. I keep clones of at least 2 or 3 past OSs just in case I need to go back. This will be very important when Apple rolls out the next Operating System because it will no longer support 32 bit apps, if you use any. Mojave is the last one that does. When they roll out a new OS, I wait until the at least the .3 version before I put it on my main computer drive, but will test earlier versions on a clone (other than my back up) to see if there are any problems. When all is good, I clone the test drive to my main drive and the test drive then becomes my back up. Both SuperDuper and CCC can be had for free if you just want to make an exact clone. Full paod versions have a few extra capabilities like SD's Smart Update, which just copies the changes you've made since last time instead of reduplicating every file. Saves a bunch of time.