Repeating parallel upgrades to Content Server - how much do we need to tear down each time?

We're planning a parallel upgrade from CS 16.2 to 22.3. We've tested the whole process successfully a few times but each rehearsal we strip down the target system completely so we re-install CS and OTDS. So we're wondering just how much we need to uninstall each time we perform a rehearsal. For example, could we just replace the database with the latest 16.2 version (from the production system) and simply go to the admin pages in 22.3 (assuming nothing has changed in OTDS)? Or should we just stick with the current process of uninstalling CS and OTDS? It's not a massive issue but obviously we'd like to minimise the down time for the production cutover if possible. Thanks.