Unless your "100 plus" priority channels are most all on trunked systems, with that many priority settings, you'd hear a very significant break in reception of whatever you are currently hearing when the scanner takes a time out to check the channels set as priority. For conventional frequencies set as a Priority, the scanner has to stop whatever it is hearing and go check the tagged priority channels. That would result in a very noticeable break in reception. The more frequencies set as priority, the more annoying the interruption.
For trunked systems, you have to set the system for "priority ID scan". That setting, needed for each system with one or more TGIDs set as priority, is under Options for the system. However, trunking priority is separate from conventional channel priority. For conventional entries, the scanner does break offto check your flagged frequencies, causing the hiccup in the audio. On a trunked system, setting "Priority ID Scan" prompts the scanner to check the control channel data to see if any of the IDs you set as a priority is active. That's 'behind the scenes', and does not introduce the noticeable gap in reception. When the scanner is in a trunked system, and checking that single system for priority settings, it will not be checking your conventional priority channels, nor priority talkgroups in any other trunked system.
This is just me but you may be expecting too much from 1 scanner.
This is why I run 16 scanners in my main home scanner rack and have a 4 scanner portable scanner rack I take to work plus my 6 plus Handheld scanners.
I agree 100% with budd. If you have anywhere close to that number of conventional channels set as a priority, you'll miss more transmissions than you hear, and what you do hear will be so broken up as to be practically useless.