I would look at the system you are monitoring and plan it out. I usually put the talkgroups in 3 parts. Always want to monitor, Sometimes want to monitor, and Never want to monitor. I then put the Always set below the threshold, the Sometimes set just above the threshold, and the Never set further above the threshold.
So as an example, you may not want to hear DPW groups from 10 municipalities every day but want to be able to turn them on during a big storm. You might have the Threshold at 70 and the DPW at 75. During the storm, you bump the threshold up to 75 and you are hearing them.
Obviously, with a small system, it may be easier to change one or two groups individual priorities whenever you want but in a bigger system, it can be helpful.