There is definitely a time that it is too long. Yesterday's three plus hours was a while for me and I was sore the last hour plus every time you change activities (sitting vs standing vs walking, etc, you feel the soreness. But for me, doing it for my Domme, that's all I need and I'm able to push past it. If it was just me. I'd probably have taken it out after an hour.
No plug yet today but expecting the instruction this afternoon.
I'm plugged now and wearing blue and white silk panties in my office. My mistress has me wear both home on the train each evening and then change/remove my panties and plug at the train station when I arrive near home.
For the guys, going for a long bumpy drive at times with the Helix in you is fun. I didn't get a big O but I was in haze/daze. I had to work hard on concentrating on my driving at times.
Mistress wanted me to be plugged on my ride into work today. When I got to the office, the base (steel, jeweled) had actually started to go inside me which I guess is the opposite of potentially falling out. Thankfully was able to extricate it but might be time to consider a larger based plug. I wore the plug for my first hour at the office too...now a few hours off before I wear it again towards the end of the day.
My experience is steel stays in place better than silicone when it comes to work and bending.