I could go through 20-30 510's when I am blending and testing juices. I agree that tanks or RBA's are just not suited for testing because cleaning them is far more difficult than cleaning a 510.
Even if you copy a highly rated recipe, how accurate are the measurements? Is the person's eyedropper 20/ml or 40/ml? Do you have the same exact flavor from the same supplier? For instance, a Flavor Art blueberry will be very different than a Lorann's blueberry or Flavor Apprentice's. Also, our tastes are so different. Are you using the same base PG/VG/Nic ratios as the original recipe? How do you steep? Etc., etc.,etc.
You cannot stock every single flavor out there. Well, I guess you could, but that would get expensive-not to mention the storage space required.
In other words, one is constantly tweaking recipes.
I always start low and work my way up, and mix 3 ml test batches. I use variable volume micro pipettors which are very, very accurate but expensive. Our lab gave me the old set when it went over to electronic ones. Weighing with a digital scale ($20) with .01 gram resolution is far more accurate for most but the arithmetic is a tad more complicated.
My procedure was to try a mixture, and then toss the dripping atty into a hot US cleaner with baking soda. Tweak, taste, and toss into bath. Dump the bath, fresh bath with baking soda, fresh bath with purified water, dry burn.
It was a pain.
After getting down to my last 5 510's, I was thinking about ordering more, but at $5/each, the investment seemed questionable. They would die sooner or later.
Then I saw these $5 RDA's on Fasttech. They have a wide base and decent sized posts and screws for an easy rebuild with mico coils and cotton. Now I taste, pull the cotton, dry burn, rinse, shake off the water, and pull a fresh piece of cotton.
It's a fast, easy, and economical way to test my juices. These cheepo's will last forever.