Yeah the whole idea is to figure out what works best for you and present that to your client as the way you work.

The reason full-time freelancer prefer dayrates is that if someone books them for a project they want to know they're being paid for a full-day, not just say 5 hours.

Some people work on an 8-hour day, some on a 10-hour day. That just means that when you get booked the client is guaranteeing you a full day-rate, even if you only end up working 6 or 7 hours.

So, for example, if you told your client your dayrate was $250 for a 10-hour day that breaks down to $25 an hour, but it guarantees you the full 10 hours. After the 10 hours you would charge overtime, typically at time-and-a-half.