Caps off is to evaporate the alcohol from the flavoring.
An ultrasonic cleaner will accelerate the airing and steeping considerably.
I have a $30 el cheapo but still get fully steeped juice in hours (over the course of a day or so).
It's worth the $30 to me and will probably upgrade to a more robust UC unit YMMV
A lot of vapers do the caps-off thing in a closet.
Keep the cats out of the closet and voila!
After discovering the importance of steeping (and the night-n-day difference it can make to flavor), a UC is the next vape-related *thing* on my list of "Random vape Gear/Equipment I Need To Make Life Easier" list.