Claim: Lever machines are slower than other types of machines as they need a longer extraction time
Not really true. Any lever extraction that goes beyond a 30 second run time (i.e. from when the coffee starts to flow until blonding appears) will have an unpleasant wooden taste, similar to that you get from sucking on the end of a wooden pencil once you’ve chewed through the paint, i.e. over-extracted. In our experience there is something magical about a 27 second extraction on a lever machine
If you want to add in the pre-infusion time to the equation, then yes, there is a case for saying it takes longer, but again this depends as pre infusion can run from as little as 3 seconds for dark roasts on small doses to more than 15 seconds for light roasts on high doses
There is no need to back flush as the pressure tapers away to zero at the end of each shot so you don’t get any suck back that you get when a pumped liquid has the pump pressure shut off (this is not specific to espresso machines, it applies to any pumped liquid)
You shouldn’t need to clean the shower screen on LONDINIUM I, or indeed any similar kind of spring lever machine more than twice a year in a domestic environment and once a year would also suffice if you don’t suffer from an obsessive compulsive disorder. I still remember my father saying that the fewer times you take something apart the longer it is likely to work. As far as I am aware this advice is still in force
Seals only need to be replaced when they start leaking. As you have seen in the video this is a simple task and should not be required more than every 3 to 4 years in a commercial environment, quite probably much longer in a domestic environment