This is exactly why I prefer the Nespresso, there are so many variables to control with pulling my own espresso shots and I really don't want to be bothered with any of it.
I just want a consistent, fresh, and marginally professional espresso without having to become an expert at all the above. It also goes without saying that getting all these variables dialed in, for the most part, doesn't even happen at local coffee shops. There are a few in my area, but they're all at least a 10-15 min bike ride away.