If my RV had been sitting for years I would bleach or HP the system.
If you are dewinterizing or freshening the system of a frequently used unit, you are just removing stale water taste/smell, if any, to prepare it for use.
Leave the juice in as long as you want to so you feel good about the process.
FOR SALE 2014 BOSS 6.2L F350
2012 Surveyor SV264