Sorry for replying your question late, it was alwaysin mind to reply but
there was no chance last days. It happened with me as well in the 24 plates
that the wells outside are drying faster. this is obviously becasue because
the wells outisde have more exposure to the (dry) air outside the plates.
so, all ideas that avoid that situation will help, as following for example:
1. while drying under the laminar flow, put some microliter od sterilized
water in all wells which are on the side of the side that te air is coming
from and you might add more, or better than that you might put always an
extra plates that have aonly water as a barier between your experimental
plates and the air. this will let the air coing over your plates having
almost the same amount of moisture. so, it will dry more in the same speed
(specially if you turn the plates from time to time).
2. with keeping the plates, might the same ideas of surrounding your
experimental wells with wells that contains just water, it depend on your
stack organization !. Parafilm arounf the plates and/or extra container with
water into your incubator might help to raise moisture level.
I would like as well to hear if you have got some crative idea replying
your question. good luck.