Here are the Bianca valve photos I neglected to post....

Thanks for the photos Graham J, so how often do you need to descale? And did you soak these in the descale solution? I mixed my water with Partial RO and filtered Tap water thru Brita and kept the TDS not to exceed 60ppm. I also have Lelit's resin filter inside the tank as well, hopefully I will never need to descale the Bianca. I heard as long as you don't go over the 60ppm you will be good to go, not sure if that is a true statement?

David

How often? I haven't descaled this Bianca yet. As you can see from the photos, there is no need at this time. Only 1014 shots so far though.
I wouldn't descale the E61 until I have to and I'd judge that by a change in the flow rate of the needle valve. This is easy to measure with a scale - just take two or three paddle positions and record how much water flows from the shower screen in 30 secs. Or just remove and check the valve once or twice a year. It is easy to strip and rebuild the Bianca E61 group without special tools.
Other parts of the machine may need descaling at some point, but that will be indicated by some other change in performance. It doesn't really make sense to descale unless substantial deposits have built up in the boilers or E61. Bianca has servicing ports in the case to allow easy removal of the heating elements to check and service. you could do this yourself every couple of years, depending on usage, or leave it to a service agent.
So, to sum up, it's not a large or complex job to check the machine for scaling and I'll personally not be descaling to any schedule.

Regarding Lelits inbuilt resin filter, I'm guessing you are using the filter counter on the water reservoir? If you keep this on the replacement schedule and avoid high hardness input water it could well be that you will never need to descale, but a service check of boilers/elements and E61 after say two years or 5K shots will tell you what you need to know.