HeatSticks are specially designed to fit in to the IQOS Holder. They may be smaller in size than a cigarette, but that doesn't mean their duration and your tobacco satisfaction will be shortened.
In fact, IQOS and HEETS are carefully designed to provide you with tobacco satisfaction and duration similar to what you receive from cigarettes, with each HeatStick lasting up to 14 puffs or 6 minutes on average.
Longer, gentler puffs and breaks in between would extend the duration and increase satisfaction from your HEETS. Drawing too often and too deeply can cool the blade, which will produce less vapour and shorten the duration of your HEETS.