I use the woofers cooling stands too, don't use it till your done, between bowls I use the lid from the reload.
The cooling stands work brilliantly, but you want to keep that heat for your session.
When I'm chaining multiple bowls, half or full bowl, I reheat till the visual indicator is at the middle marker.
Also, wand induction coils, batteries and battery power level will affect how it all works too.
As the the power in your batteries lowers, when the display is showing 2 bars, you might need to keep it on the power longer, the middle marker on the VI might be sufficient, but you might need to leave it longer, maybe until it's between the middle and last marker, or indeed on the last marker.
When mine gets down to one bar, I need to keep the power on till it gets to the 3rd mark to get the same roast on the bowl.
Once you've learned how it all reacts, there's zero thought process in all of this.
Enjoy chaining bowls, this device is superb, new meds arriving this week, WOOHOO
It might be your insert, it's weird, I have three of them, my original seems slightly different from the last two I got.
One of them I've passed around other people with a community head I got (one to share around and let folk try it), they've all had issues seeing the VI through the wand adapter.
My original adapter, I can see the VI perfectly, it's so clear, even when it's pitch black, the light from the wand is enough to let me see what's going on, yet the two I got later on, where the bottom meets the sides, there's more distortion, so it's really hard to see the VI when it's moving, I'll end up moving it here and there to try and see it better.