I would be more than happy to answer that question, but in order to do so I need to ask a question first.
What are you using to measure your resistance and what is it's accuracy?
The TWO times I actually built extremely low ohm builds, I used my Extech 580... Which I only happened to own because of other work I do... I certainly wouldn't have spent $700 on a meter to build coils... I have my doubts as to rather he did either...

Of course I know you do too... LOL...
Anyway, back to the point... Why did I only build extremely low twice? Because after doing so I kinda stood in the middle of my kitchen and thought to myself "WHY???"
I mean hey... I get it... I know guys who own supersport bikes who do nothing but ride them moderately on the street... I on the other hand was a member of NESBA and lived for track days... Then I also knew a few guys who were die hard racers... their entire life was racing...
For those who choose to "cloud chase" and push their equipment to the very edge, and sometimes beyond, rather for competition or just the occasional giggle, I totally get it... But then there are those who remind me of the guys that would get a liter bike as their first bike, slap a 1/5 throttle on it, power commander, race exhaust, etc and then go out on the street and ride like they thought they were the universes gift to racing... and I've personally known two of them who no longer ride... One because he suffered the consequences of his stupidity and the other who no longer has a life to live. Not to mention the countless stories from other forums...
The point is... if that's what you love to do... then by all means... pursue it... learn everything you can about it... understand everything about it and take it to the edge... Just as someone like me does with track days... or a racer does every time he sits at the starting line waiting for the flag...
but remember... that same racer has dedicated his life to what he does... he has extreme precision in his wrist when it comes to the throttle... He knows the exact power band of his bike... He knows every race line like the back of his hand... He knows the exact limits of his tires, not just now or later, but through the entire cycle... And he has a team of people making sure every piece of equipment is in tip top shape all for one very specific purpose... to keep him safe...
The jackhole who bought a bike last week and decides to go racing on the street isn't a "racer"... He's an idiot...
Now don't take what I'm saying the wrong way... I'm not saying you're "that guy"... But... try to understand something.... Just as "that guy" sits at a stop light and cranks the throttle and let's his engine bump off the rev limiter... Not because it serves any purpose... but only to say, "Hey! Look at me!!!!" well...
You came in here and posted an "extreme" setup... then asked, "Is this normal"? If you know enough to run a setup like that, then you KNOW it's not normal... In other words, it smells an awful lot of a "Hey! Look at me!!!" post...
Now you ask what the lowest you should vape at to be safe... I don't want to confuse the issue, but again, if you know what you need to know to be able to safely run extremely low ohm setups, then you'd never have to ask that question... because you'd already know... A racer doesn't say, "Hey, what's the safest speed I can enter turn 3?" He knows enough to KNOW... If on the other hand i'm misinterpreting your post, and instead you're saying, "Hey, if what I'm doing really isn't that safe, then where should I be?" then honestly, I'll just share this.... Back to the beginning of the story...
Why only twice? Because I realized that there wasn't a point for me... I realized that if I'm going to "sub-ohm" I'm happier in the .4 to .5 range... And actually, as of late I've come to find that generally I prefer a ~1ohm build on a regulated 50watt mod more than most sub-ohm builds... Why? It's just more enjoyable to me...
So again... if that's what makes you giggle, then by all means... But do your research... and research isn't saying, "hey, what should I do..." It's learning enough about the basics to be able to answer that question for yourself....