In my experience, LR (Low Resistance) atomizers are hotter than the standard versions, thus they don't (usually) last as long as the standard atomizers but you can prolong the life of the LR atomizers by not taking many draws in rapid succession. Instead, take a draw or two and let it cool for a bit before taking the next draw. Also, sometimes it's hard to tell if it's the atomizer at fault or if it's the user that is causing the atomizer to have a short lifespan. Either way, their are many variables to considers, such as,
Do you clean your atomizers? if so, how do you clean them and how often?
Is the atomizer modified in any way? does it still have the mesh, bridge, wick, etc?
Is this atomizer just a standard LR? or is it Cisco made, Ikenvape made, etc?
Do you overcharge your
batteries? or do you take them out as soon as they are charged?
What device are you using?
For a LR atomizer to last 3 weeks (plus your friend who used it) is pretty good. The range on the LR atomizers can be from a week to a month and sometimes more but rare.
Hope I didn't leave anything out but I would need more information from you to discern the problem.