Speaking from my own experience, I don’t think it is a good idea to leave the Twilly wrapped on the handle for too long…
I am not in a particularly humid environment, and I have humidity control in my closet, but there was one time when I left a Twilly wrapped on the handle of my Kelly for about a month… when I finally remembered to unwrap the Twilly, the painted leather seal of the handle became sticky!!! I immediately brought it in to a store to let the craft person check it out. The craft person told me that it would be fine this time since it was not too sticky, just let the handle air out, and the problem should resolve on its own. However, he also cautioned me that the leather needs to breath, and recommend to take the Twilly off everyday or every other day after use. Our hands sweat and the humidity can get trapped in the silk and soak onto the leather. If it is left on for too long, it will eventually damage the handle. Hermes can always repair or replace the entire handle, but that will not be cheap.
From that point on, I always unwrap the Twilly from the handle of my bag everyday. It is annoying to have to constantly wrap and unwrap it, but with practice, it has become a type of soothing therapy. I hope this helps!
TIA for any input.
