depends on the water also going in, if your northwest you get really good water, down south then out of luck,
unless you test whats going in you dont know how your filter is doing, me personally, i use rodi as i know whats going in and in 15yrs time id never have to descale a boiler,my current machine has no boiler, but the internals will still be spotless,
theres debate over dr pavlis water muting taste, vs something like third wave, but third wave will scale eventually, and for me having to rip a machine to bits to clean it is a massive no no, for the sale of a £80 filter system and 20 mins of my life once a month