With the inordinate amount of time Musk spends on Twitter, I'm gonna go ahead and assume most of those 90 hours are not productive.
If you want to know why he selected the features for the Cybertruck, go back 1 year when he asked the desired features on Twitter. It's crazy how many of those small looking features (like a bed for normal sized / tall people, lighting in the back) were included in all models.