I removed it after a week. I thought of leaving it on because it did then resemble a Sennheiser headband. Some folks work the headband like kneading dough. I softens up the foam rubber. The Velcro was about 1/4" wide.
I've found solderdudes EQ advice is spot on with a minimum of filters to get great sound. I understand the Harmon curve but I don't follow it.
A lot of headphones just don't need the bass boost (for me) and some that do can't handle it. I like the original signal as unmolested as possible
YMMV.