Smart move. The UI wasn't that great, the product wasn't intuitive, and why would you have two inbox clients from one company? Normal people don't use Inbox, they just want to use regular Gmail and not think about it.
Some (if not most) advice is pretty self-evident. But number 15 is interesting, about the legal profession and how lawyers round time when billing clients:
Rounding is a common practice in the legal profession and is the reason why lawyers can end up earning more than they actually work. Because they bill by 1/10th hour, a 30-second phone call and a 2-minute email are both rounded to 6 minutes for total of 12 minutes. This way, they can easily bill 8 hours in 6 hours (while staying perfectly honest).