Maybe this isn't as helpful, but I currently charge my pro every night. If I remember to charge it, then I have not once had an issue with it dying during the day. I do come close on business trips with long flights. If I am leaving town I may end the day with <10%.
I take a lot of notes (20+ pages per day with illustrations), work in productivity apps, constantly listening to music and working on emails. I have cellular and Bluetooth on the entire time. About 20% of the time my be spent surfing or watching something for entertainment.