Well got mine from ctd last week ,used it twice once on a good floor once on a not so good floor.
On the good floor i got perfect coverage,no back butter worked a treat,on the not so good floor had to back butter but was still getting 90% coverage on average.
On the good floor i reckon i used less addy than i would with a 12mm solid bed trowel,was around 10m2 and i had change outta 2 bags,on the other it was 18m2 and i used just on 4 bags.
On the good floor i got perfect coverage,no back butter worked a treat,on the not so good floor had to back butter but was still getting 90% coverage on average.
On the good floor i reckon i used less addy than i would with a 12mm solid bed trowel,was around 10m2 and i had change outta 2 bags,on the other it was 18m2 and i used just on 4 bags.