Jrong, I can't tell for sure since I play a lot without film in the camera. Still working on my AF technique and everytime I read something here I deplete batteries afterwards 🙂
The thumb focusing with the back focusing button for example or training to judge focusing by listening to the AF sounds. I have this camera for nearly four years and there are still possibilities to be explored I haven't thought about.
October 2004 in Cuba I brought two spare batteries just in case, I didn't know how much I had shot on the old batteries, and didn't need them.
I've used that set of batteries from january 2005 to august and I shot the 10 rolls Tri-X which where delivered after my vacation, 5 rolls of Sensia 100, 5 rolls Tura Pro 400, 2 rolls FP4 and maybe 3 or 4 rolls of cheap Agfa colour film with this set of batteries. Then I replaced them while they were still working and depleted them testing a newly aquired and very used G1.
I once had a pair of Panasonic batteries from Walmart which died after less than 20 rolls. Now I use Ansmann branded batteries I buy via eBay for some 2.50 to 3 Euro a piece. I bought 6 last year in august, one set is in the G1 and the second in the TLA200 flash, the third is still in my bag and the G2 runs on my spare set from 2004 🙂