I am really bummed that you have had a problem with gel curing in your pots as you have worked. You are also right in the fact that you are not the only one. Out of an aproximate 500 kits sold, there have been 2 others that have had the problem (and possibly even a few more).
You are also right in the fact that it is ridiculous to contemplate putting the lid back on in between every scoop. I too would be very frustrated with this.
Doug sent a great email on why this is happening and I will endevour to post it tomorrow, but I will paraphrase here in the meantime.
Brisa uses a very low count of photoinitiators (hence the need for high efficiency UV bulbs) however the photoinitiators used are highly active (sensitive to UV light). That allows us to get a solid cure with high emission UV. Highly active photoinitiators are very sensitive to UV light and sunlight emits more UV light than even the Brisa lamps.
Therefore, sunlight can have a very strong effect on Brisa in particular. Just as you can get just about as much UV exposure sitting in the shade as you can in direct sunlight, some salons can still have a lot of UV emissions in them even though the nail tech may not be sitting in direct sunlight. I feel that this has been the situation in all 3 cases that I have known about this happening. What has also supported this theory is that these salons did not even do gels before Brisa (though Im not sure if this is the case with you) therefore they were not expecting a problem.
Still the fact remains: No UV light=No cure.
It seems you have come up with a very smart way of limiting the UV light exposure suring application though I (like you) still wish you didnt have to
Brisa could always be switched to use slower reactiving photoinitators. This would mean that it would be far less likely to set in your pot. However the catch is that a great deal more of these PI's would have to go into the product and as a consequence, you would increase the aging of the system.
I hope that helps shed some (non UV) light on the problem