The phrase invites scepticism, and it should. Plenty of things sold as one-day work are simply rushed. The distinction worth understanding is what is being compressed and what is not.
What is not happening in a day
Your bathroom is not being designed, measured, fabricated and installed in a day. The measuring visit happens first, and fabrication takes real calendar time afterwards. What happens in a day is the installation.
Why the installation is quick
A traditional tiled shower is built on site, piece by piece, with drying time between stages that no crew can compress. A solid surface system arrives as a small number of large panels already cut to your walls. Fitting them is assembly, not construction, and assembly is fast.
What a real one-day install includes
Tear-out of the old bath or shower, inspection of what is behind it, fitting of the new pan and panels, sealing, fixtures and fittings, and removal of the debris. If any of those is being skipped to hit the deadline, it is not a one-day job, it is an unfinished one.
When it takes longer, and it sometimes does
Moving plumbing takes longer. Water damage found during tear-out takes longer. Taking in the floor, the vanity and the toilet takes longer. Any contractor who promises a day regardless of what they find is promising something they cannot control.
What it means for you
Practically, it means one day without that bathroom rather than two or three weeks. For a household with one bathroom, that difference is the whole decision.
