“2 weeks in the summer might turn into 3 years in Iraq or Ukraine”
I got out 10 years ago after retiring AGR. Even today the Guard and reserves are being used as vacation replacements. If you are in you get to relieve the active duty components so they can have a break. Now as long as he is in schools and not fully MOS qualified that will keep the deployment at bay. On the other hand if he was to branch Artillery, go to the Arty basic school to get in and then goes to med school he will be eligible to deploy as a cannon cocker. Nothing wrong with deployments and I did enjoy them because it got me away from the stop signs, cell phones and Walmarts. I knew everybody not dressed like me wanted to kill me but there was no BS.
So reservists are individually plugged into units they qualify for to temporarily replace active duty service members? A few acquaintances I have who served in Iraq and Afghanistan have a bit of contempt for reservists (wrongly I felt, the guys are deploying to war zones after all), but at least back then, it sounded to me from their stories that reservists were activated as units and placed as units in roles deemed by the active duty guys as somewhat “lame”.