Based on my experience, I think it is very difficult to build a product when doing client services work. It takes disproportionate effort to get and stay focuse

Based on my experience, I think it is very difficult to build a product when doing client services work. It takes disproportionate effort to get and stay focused and you have a mountain of distractions. The services work becomes all-consuming. I have had the same experience and strongly agree with your assessment. Furthermore, this seems to be true even if the customers are more or less directly funding the incremental development of the product. Somehow, their specific needs, slight customisations and tweaks, support thereof, etc. expand to fill up available time.