Actually, that's not how it works.

Oh man, that sounds like my kind of weekend project. Isn't it funny how a simple job always finds a way to humble you? Try mixing smaller batches and add just a tiny bit more water than the bag says, but not too much. A cool trick is to mist the floor with a spray bottle before you spread the mortar, it buys you a little more time.

Oh man, that coffee ring is a classic. I once had a client text me a blurry photo of their monitor with the note "make it pop more" written on a sticky note stuck to the screen. Your rule is the only way to go, it turns those vague notes into something you can actually work with and charge for.