The truth is most professional tile installers and dealers do not know how to check a floor to assure that the installation will not fail because of deflection.
Construction plans are supposed to take this into account, but what the plans say and what the floor does are often two different things.
How many times do we need to screw-up the schedule and aggravate the customer with an add-on before we realize that there is a better way. The guys on the other end of the building figured this out about 50 years ago. Their product costs much less than ours, the labor is much less sophisticated, and their liability is way less.
The person that initially looks at the job simply sets the laser on the floor and shoots a target or two across the room then moves the target across the room and it will indicate exactly were the floor is out-of-flat and how much. Then a few simple notes on the diagram and a very short but informative discussion with the customer and everybody has the proper expectation of what needs to be done, and there is no surprises when installation day comes. The customer recognizes your professionalism and will even pay more because you have demonstrated the ability to do the job properly. This is invaluable. And for the installer, any low spot in the floor gets a small plastic pin that gets snipped off to leave a dipstick for his patch material (Photos 1-3), and it also doubles as a screed point to feather out the birdbath (Photo 4).
With over 60 percent of homes being out-of-square, wouldn't it be prudent to tell ask the customer which wall she would like to be straight and prep her for the fact that other (less important) walls might run off. If the same laser shot two 90-degree lines down both major walls, anyone could show her where the problem lay (Photo 5). This even works instantly on 45-degree walls too. Speaking of square, wouldn't it be better to give installers a square cut instead of a parallelogram for each job? This is why the average warehouse person adds an additional three inches to each cut. Do some math here and you'll see $18,000- $25,000 per year in useless landfill.
Remember that lasers can help you do measurements, layouts, and more with greater accuracy, and in a fraction of the time. A laser tool designed for flooring is arguably the most valuable tool you could have.