You are probably wrong. It should have no affect. Along the same lines, changing light bulbs in a flashlight will not affect batter life.
That's my opinion. I could be wrong.
switching
tanks would not affect battery life IF both tanks had coils that had the same resistance.
this, unfortunately is almost never the case. Unless you rebuild your own coils, your coil resistance can vary, even on the same clearomizer design.
I rotate between 3 clearomizers and the currently installed heads are all rated at 2.5 ohms. However they each vary from 2.4 ohms to 2.8 ohms.
Using ohms law, let's assume a 3.4 voltage output of the standard eGo fixed voltage battery.
If you had a 2.4 ohm coil, you would draw 1.42 amps.
If you switched to a tank with a 2.8 ohm, you would draw 1.21 amps.
This is a significant difference in draw. The 2.4 ohm heads draws 17% more amps than the 2.8 ohm head. The flavor and taste of the 2.4 head would be better, but the battery would last only 4/5ths the time.
So yes, frequently changing clearomizers with different resistances can affect battery life.