Imo it depends what you're doing. I would say for manuals and pumping then at least 1-2 rest days per week. For extenders, you can do 7 days a week but if you are literally doing some kind of exercise 7 days a week then you should take a rest week every 6 weeks where you do absolutely nothing except things that may aid in recovery. I wouldn't destroy your dick 7 days per week though, just asking for an injury.
I do manuals 4 days per week (use bathmate for warm-up and warm-down). ADS 7 days per week (when I have time). Clamping on a 1 on/1 off schedule. MagVolt I use to aid recovery when I'm not doing anything else. I rest every 6 weeks and will be doing a shock routine on my last day to exhaust my penis and then a full week off for recovery.