I rarely consume much more than 10 grams of dry leaf a day. That's 1 or 2 sessions at midday and/or in the morning. This is the amount at which I haven't noticed any adverse effects.
I typically drink about 6-8 g of high mountain oolong per session, which provides some 6-8 cups under 100 ml each. Another session might consist of 3-6 g of Chinese green tea resulting in 4-7 steepings/cups.
In total, that makes about 8-14 cups per day. Nothing is ever accurate, though.
At least 5, as many as 20. I like to wake with Japanese green tea or black tea, sip oolongs (or any interesting new acquisitions) as I go through the day and whatever takes my fancy in the evening. If I'm at all restless at bedtime I finish with a few infusions of the only herbal tea I drink, a nice chamomile/citrus blend. Like John, I always seem to have something brewing; it's hard to keep track. Tea is the gentle thread that runs through all of my days. I'm always grateful for it.
I brew up to 4 different tea sessions daily, some solo, some shared. Since my cups vary from less than 100 to more than 500mL, it's probably simpler to say that one most days I drink at least a liter of tea, and many days it's probably closer to 2 liters. I do tend to drink my tea fairly dilute, and may extend my infusions well into the sweetwater phase, so that might take as little as 10 grams of leaves for the total day's drinking.
Usually just 1 session a day, which would be 3-4 cups. Usually starting in the morning shortly after I waking up. Though every once in a while I'll do a houjicha session at night. If I have sencha after 5pm I always have trouble sleeping.
For me it can vary a lot depending on the season. It also depends on if I've discovered a new tea that I really like. Right now, since discovering these 2 TKY's, I think I'm drinking maybe....4-5 cups a day sometimes as much as 7 if I throw in a cup or two of Lapsang
ETA: speaking of...I'm wondering if I should cut back. I was experiencing some major insomnia issues the last time I was drinking this much tea. (of course, it was black tea, brewed by the urn-full, and VERY strong....). I ended up having to go 4 months without ANY tea in order to get myself sorted out. it was HELL I tell you