In the old days, especially in victorian times they never used cement they just used lime and sand to set bricks. So rainwater or a brush just cleaned them.
I love new build cleans, I never use an extended lance because you cant get the desired results.
You need a good powered machine with a pencil jet or a turbo nozzle if you know what you are doing.
A backpack pump sprayer 25 litres of brick acid and away you go.
But when cleaning new houses its best not to be over zealous as you pull out the mortar or even worse damage the brick.
Its always best to wash down new houses before applying any sort of brick acid as this prevents any staining.
But public liability and method insurance is a must, because the last thing you want to do is to cause damage to £500,000 house.
I wont say its easy because its not, but the results are instant and you get a great sense of achievement. (maybe I am sad)
Its cleaning of old brick thats the pain, I usually recommend a sandblaster.