If you get offered a free recast, it's a no-risk way to make your mandatory payment lower.
I paid down a bunch of principal early in my mortgage. Then, just 2 years in, I read a bunch of articles and forum posts which led me to prefer NOT paying off my mortgage early (the rate is low, and I would rather have the money in my brokerage account for FU money, moving, and a future downpayment).
A couple of years after that, my lender offered a free recast. I took it, and now the difference between my old and new payment gets automatically invested in its own brokerage account.
If I do end up staying in this house, I'll consider paying it off when that account exceeds the remaining balance.