Good clients --- in fact, it's possible that all the clients of my previous practice, over 10(!) years --- will uniformly accept daily rates. In high-end contracting work, daily rates are industry standard. If you have the option to bill on a daily increment, why would you ever bill hourly?

You charge a very high hourly rate today. Savvy clients are happy to pay it. Those same savvy clients would be happy to pay on the day increment if you multiplied that rate by 8. And:

* So would slightly-less savvy clients! Clients will balk at a high hourly rate more often than a daily rate. People are accustomed to paying for service work --- housekeeping, car maintenance --- at an hourly rate, and have price anchors in their heads that your rate blows past. You sound more expensive hourly.

* You get an automatic 8-hour commit for every project you do without even trying

* You can repurpose the brain cells you're spending today on being really good at time tracking to getting really good at Jakiro in DOTA2 at no additional cost to your business

* You can still throw 3 hours per day at a client, and the next 3 hours of that same day at another client; all you have to do is be honest with yourself about how you're doing. And again: part of the terms of a day rate is, you get to round up.

* You can still work more some days and less other days. Your fee structure is not your delivery date.

* You don't need to explain ramp-up and ramp-down to clients, because it's built directly, quietly, and non-negotiably into your fee structure. It's a conversation you simply never need to have.

The two points it didn't seem like you followed from my original comment:

* By working with a contractor instead of hiring a full-time developer, your client is paying for projects to be completed on a specific timeline without the overhead of an employee on a deterministic schedule. There is a huge amount of convenience and de-risking implied in that. When I talk about burden-sharing, what I mean is that it is more than reasonable for part of the cost of that convenience to be "you get me for a day at a time, whether you need the whole day or not". The alternative they're looking at is "you get me for 2 years at a time, whether you need me that long or not".

* When you have an hourly rate, any time you do anything free for a client, you risk creating the expectation that that thing should have been free, and that it's reasonable to ask for that free thing in the future. But very few freebie tasks take a whole day. The client can intuit that a day's worth of work is going to cost, but still feel comfortable asking for a 30 minute phone call without wondering whether it's going to be invoiced.