Agree with all Mongos' points. We just looked at a major fail (new build, obviously a pro didn't do the tile). But note the dark areas near the walls in this picture. This is what happens when there isn't proper pitch. That water sits in those stones. Now, in this case there are many other things wrong as well. Pretty nasty. Make sure you get an experienced pro for all the reasons Mongo stated.

I mostly do epoxy grout for all my shower floors. Pre-seal the floor first if you do this to avoid staining issues with the resins potentially.

Mongo’s points are great ones....If you are using a contrasting grout....it’s better in my opinion To set the pebbles individually. Even if you take your time to fit the sheets together you can sometimes still tell where the sheets are once its grouted. It takes more time but the finished product looks more natural. Like I said ...I tend to do this method if the grout is contrasting.

If the grout is more the color of the tile then I will try to try to dry fit different sheets until you achieve a tight fit. Grout near the same color as the tile is more forgiving about showing inconsistencies.

I like the sliced pebbles underfoot. It gives a nice texture with a lot of grip when wet.

You want to give a shower floor with this kind of pebble tile more than the normal quarter inch per foot slope as it will help the shower floor shed more water being that there are more grout, wider joints in places.

The epoxy grout really helps though in my opinion to achieve the look and also be low maintenance for the customer.

It is a great look when done properly!