Different devices LEND themselves to be more or less consumptive, but it's driven by a lot of variables - the power, but also the build, wick, and airflow...
I mean, you could build a kayfun with a single 2 ohm coil, tight airflow and tight wicking, and sip juice very conservatively. Or you could build it with a 0.25 ohm dual, open wide, and suck through a tank in half an hour.
I'm not familiar with Genny's...but it seems to me that not many of them added bigger airflow like newer kayfun variants did - so they're probably in general not going to be guzzlers. But basically, your juice consumption is going to be driven more by your build/vape preference - are you low resistance/big clouds? It's gonna use a lot of juice!