A full day interview is excessive, unreasonable, and almost certainly unnecessary (you're also wasting your own people's time). Again, your candidate has another job and - if they're any good - is probably interviewing other places. Especially if they're not desperate to make a move, they're not going to take multiple days off in a week to attend interviews.

(And that's not even counting the awful take-home coding challenges that take multiple evenings or an entire weekend to complete.)

For a half day, allow it to be scheduled at least partly before/after standard work hours so that the candidate can just come in a bit late to their current job or leave a bit early - claiming a dentist appointment or similar.

If you don't respect my time, I'll assume that's a harbinger of how you'll treat me after hiring, and I'll walk away.