This is a very broad topic to discuss but I think about it a lot. From my experience, the amount changes over time and also the potential percentage. I think the generic recommendation is to save 10% or 20% which is a good guide, but it may not realistic if you are a student or perhaps have already retired.
What is NPS - Net Promoter Score
Net promoter score is attempting to measure the loyalty a customer has to a brand. It’s about the overall experience, over time, rather than trying to look at a snapshot in time and react accordingly.
It complements other customer channels that should be monitored and not meant to be used as the one source of truth.