I was waiting for a long time to ask this
What is the vaping time for 1600 mah (-ish) batteries with chain vaping with high currents
It won't be long. MAh ratings are a general average of how long a battery will last with normal use. 100 mAh = 1 hour. So using a 1600 mAh battery at 3.7 volts on a standard atomizer (2.0 ohm) should last 16 hours. Increase the voltage or decrease the resistance of the atomizer and you will see less than that. You'll see even less time with sub ohm vaping.
I don't (and won't) do sub ohm vaping, so I can't answer with specifics. I know that with my 2000 mAh AW 18650 IMR's, using a 2.0 ohm coil in a AGA-T2 rebuildable on a Provari, I get far less than the 20 hours that the mAh rating says I should. (I do get 20 hours with a 2.0 ohm cartotank, so yes a RBA pulls way more amps than typical atomizers do.) My guess is you might only get half the listed mAh rating time with sub ohm.
(Hint 1 - get plenty of batteries)
(Hint 2 - resist the temptation to purchase a battery solely on a higher mAh rating, if you are going to do sub ohm vaping safely you NEED a battery that puts out high amps.)