There can be many different reasons why a person would describe a vape as "too strong". Does it feel harsh/grating so it makes her want to cough? Or it simply produces too much vapor too fast so it feels overpowering (like gasping for air) and/or hot? Nicotine harshness can be tamed either by switching to a different system that uses "nic salt" type of e-liquid (as opposed to uses freebase nicotine type e-liquid) and/or by lowering the e-liquid's nicotine dosage/strength. Whereas getting overwhelmed from bigger clouds can be remedied by switching to a different device/setup like suitable for MTL (Mouth To Lung) and/or for restricted DL (Direct Lung), also known as restricted DTL (Direct To Lung) or "restricted lung". Such a setup uses typically less power (watts) than a (less restricted) DTL setup.
Another factor to also want to take into account is that PG (Propylene Glycol) can cause a type of harshness known as "PG harshness", that, if the PG content in the e-liquid is too high, can irritate the throat and lungs of some people (myself included) more compared to some other people. Those who are sensitive to this type of harshness might want to try choosing the type of e-liquids that contain more VG, less PG. Personally, I, generally avoid anything that has less than 70 percent VG. I find that vaping on high VG also helps to reduce nicotine harshness, a whole lot actually. The combination of high VG and high wattage DTL is what allows me to choose a low nicotine strength (when I switched from smoking cigarettes to vaping, I started at just 4.5mg-5mg of nicotine) and still be able to absorb enough nicotine into my body fast enough.
The downsides of this are that high powered devices typically cost more money, they consume battery power more quickly so a device with multiple removable batteries that can be charged with an external charger is recommended for this, these devices are bigger/heavier and usually you also need to carry spare batteries with you. In addition, you get much bigger clouds, bigger frowns on people's faces each time when they see you do that again, and, other people who vape will keep telling you how totally crazy you are, as now you're exhaling something that looks like a weather system whereas only yesterday you were saying that you were choking.
