To add on: Some words have valuable and specific meanings! We don't have a good substitute word for "exponential" that means the same thing. Please make an effort not to do this!
Sorry, but in this case, it's actually N^x. Even running PCR and gel analysis requires steps where the time is dependent on the number of samples (e.g. pipetting, walking to the centrifuge, making multiple gels)
Generally speaking, running double the number of samples requires approximately double the amount of work, maybe a little less since you're doing it in bulk.
Are you really saying that going from 10 samples to 11 samples causes a doubling (or 1.2x-ing or tripling or whatever) of the time/work required? That's what exponential means.