I'm glad you guys are having this conversation about coil builds and battery safety, and the safe limits of Watts.
But nobody has mentioned the type of juice being vaped. My friend had a build of 0,2 ohms with an 18650 battery mechanical mod. All non-GG gear. And the juice was all VG based. I tried it and it was too intense for me. Even though VG by itself (not including nicotine) does not really provide throat hit, but a lot of visual vapor clouds.
If you know about ejuice, then you should know that VG is all about less throat hit and more clouds, and PG can provide more throat hit and less visual vapor (clouds).
As someone who makes his own ejuice, I add more PG to my juice for more throat hit. I don't need to sub-ohm to get the
vaping satisfaction needed. A coil build between 1 to 1,5 ohms is good enough for me for good throat hit, and battery life, as long as I have my own ejuice with my own balance of PG/VG.
I know that some vapors use VG only ejuice and for those, sub-ohm is needed to get good throat hit. Don't forget about the type of juice being vaped, and how that can be factored in with your coil builds. Some claim more flavor with sub-ohm. And others claim more flavor with a 2,0 ohm build.
Everybody's different when it comes to vaping. And I'm glad we have our options to set up any kind of ohm coil we like. We cannot do that with a cigarette.
I am not a cloud chaser. And I don't need extreme sub-ohm set ups. I enjoy vaping, and I am able to achieve the satisfaction, even at 1,5 ohms at 10 Watts...sometimes more, sometimes less. And I am from Southern CA.