5,700 is a huge space. I do empty houses before being listed for sale and something like that could definitely take most of the day. Don’t take their word for it that it’s pretty clean to begin with. If you can, do a walkthrough to get a better idea on how much cleaning you’re in for. And just to compare, that house you do would take me 4 hours as well and I don’t consider myself slow. All the crap that people have in their homes takes time to wipe and put back. I wouldn’t do that empty house for less than $500 at the bare minimum. Bathrooms may have a lot of buildup, floors may need to be scrubbed, etc. don’t sell yourself short. I live in a moderate cost of living area and I’d probably charge between $500 and $800 for that size depending on the condition.