Not a chance in hell would I rebuild without one, ALL rebuilds gets and ohm test before it hits a mod period.
I would rather be safe not have a battery go in my hand or have a wire pop in my face.
I build, test, then if ok it gets fired and crimped, repeat on coil 2-4. then retest after it is complete.
Anal retentive? yes but then again I have first hand knowledge of how fast and explosive batteries can be.
Aside from ever experiencing battery failure, I am identical to you. RDA I check after coil, wick, and again after juicing before I will fire it. I do pulse between coiling and wicking, but have checked already.
Kayfun, I check after coiling, pulsing, wicking, putting on the deck sleeve, the cone, and then final assembly. Again after I fill it.
You can never be too careful especially with a mech. If you're ohms are wandering on a box, so will your volts to compensate, which isn't good, too.
I recently built a kayfun and noticed some juice in the 510 pin area, the pin had unscrewed from the deck. Had I not checked, it could've been bad.
Everyone has said the same thing in different ways, you can never be too careful, and it takes no real time. The Eleaf ohm reader is under ten bucks, and reads to the hundredth. I recommend it highly, it also makes a good build deck.
So... The answer is YES. /Thread. Be safe!