Moving custodians might be a multi-tiered process as I saw with Swan. Doing weekly withdrawals might be a broad brush approach to having runway to provide the actual sats.

All the regulatory mess is too much for my brain so who knows.

I just know that Swan took 3 weeks to finally get my account over to fortress and I was finally able to pull my sats out (I have a modest threshold before moving on chain so I was prepared to get rugged for no more than a million sats)