So is it like a every day kind of thing or like a few hours every week or two weeks?

It depends on what the ship is doing. When a ship has to transit a high traffic area it generally takes at least several hours, and possibly many hours. This will happen every time the ship goes into port or comes out of port (the USS Fitzgerald was coming out of port), and it will happen whenever the ship has to transit a high traffic area to get wherever it's going (the USS McCain was transiting the Straits of Malacca, one of the most crowded shipping lanes in the world, when it had its collision). Those things are probably happening more often nowadays than they did during the Cold War, because more of the jobs Navy ships are being asked to do are close to shore instead of out in the middle of the ocean.

It depends on the ship, but given the underway scheduling for DDG's in Japan, generically and loosely:

Repeat every 3-8 weeks randomly with gaps of 6 months every 2-3 years:

    2 hours of leaving port

    1-3 weeks later: 2 hours of entering port