Who glues their cement board?

[High Peak Tiling]

Iv been taught to glue cement board then screw it, but lately made friends with a couple of tilers and they just screw it? What do the proper tilers do?

Always glued and screwed. As per manufacturers guidelines.
(No More Ply guidelines)

 

[High Peak Tiling]

Can someone shine some light on why tiles adhesive would be used?

 

[Carl Goddard]

screw and glue ...using a mosaic trowel it barely uses half a bag on a standard bathroom floor and doesnt take long ....why not??

 

[Stef]

screw and glue ...using a mosaic trowel it barely uses half a bag on a standard bathroom floor and doesnt take long ....why not??

Should be a 6mm trowel that's used to glue the Hardie boards to the substrate.
I suppose in theory though if the substrate is perfectly flat then you could use a mosaic trowel.