It's called progress.
Many of the adhesives are suitable for most tile types but manufacturers have developed a variety of admixes to help these adhesives bond better , not only to the impervious tiles but also to the range of substrates provided.
Quoting your example X7 was a great adhesive, did everything it said on the packet, then they brought out Ardion 90 to add to it allowing it to become flexible and not require a primer. It went from £15 a bag to + £18 a bottle = £33 to do a job. Now you can buy Webber at £13 to do the job of both - that's progress!
I still do sand and cement + a slurry back on tiles/stone but it's often a lot more expensive than the correct background with a suitable bagged adhesive product.
This job has never been easier and keeping up with new technology is the only way to stay at the pinnacle of your trade.
Note - only 4 posts in 4 years - come on get involved.
Welcome back Mr doughboy.
