I too have got sucked into this 1/16 world, spent some time over the week-end experimenting with the Diorama Debris 1/16 brick mould, was really getting quite pleased with myself thinking that "Nick the brick" will be proud of me .................... then I see he has taken brick building to a new level

Anyway here are some shots of of my efforts, I basically followed the DD instructions with little tweaks . Used their terracotta plaster, 30 gms of plaster to 8g of water, with the addition of minute quantities of their iron oxide and /or their burnt umber to add some variety .
Used Nicks method for building the test wall but used strips of 30 thou plastic instead of wood to act as the mortar spacer ........ did not really fancy trying the DD's method of of using polyfilla/Spackle to act as a glue/mortar.

(by the way I did get papal dispensation from Nick to use this bond)
Was a bit concerned that DD's suggestion for applying the mortar would stain the bricks so made up a test panel

Top left, the mortar was applied ( polyfilla ready mixed coloured with some cement dye buff oxide and a very small amount of black and thinned down slightly with water ) excess scraped of and the bricks wiped with damp cloth
Middle, bricks darkened slightly with thin water colour and then sealed with Dull cote. Mortar then applied as above , excess scrapped off and wiped with damp cloth.
Bottom applied as directed by DD, excess mortar kept damp and picked of with wooden toothpick no other techniques used other than a light brush at the end when all the mortar was dry ( did try to angle the mortar with the edge of a blade when it was still damp)
Their method is the best , IMHO
Final shot is the brick pillar built up a few more courses , 1/16 is big!, mortar applied as per DD's suggested method .... tried to leave a few places where the mortar has started to fail and fall out

That's as far I have got, now need to try and alter the basic brick tone as the terracotta colour while OK for some brick types is a bit too light in colour for what I am trying to achieve