My sets are in the stock cases (have 5 or 6 of them), bulk extras are in their packing plastic tubes in bins by size (some loose ones in there too), and loose ones in a tool box drawer. Yeah, I admit to not separating them so they can't touch each other in drawers. I'm not driving down bumpy roads with them banging into each other. I'm probably wrong, but honestly if you set a tap next to another tap, will it actually dull? There will be responses saying "No, don't them them touch each other". But I'm more of a "prove it to me" type of guy.
My cynicism started after hearing a seminar by Amar Bose of Bose speakers around 30 years ago. He was a professor at MIT and required all of his grad students to check out the book "The Emperor's New Clothes" from the library. They were instructed to transpose the story, everywhere "clothes" was written, they substituted "audio equipment". Everywhere it mentioned the people or emperor, they wrote "audiophile". His point was an audiophile will say "Oh, this $2000 Nakamichi 500 receiver sounds far better than this $100 Panasonic 100 model". The Nakamichi only has 0.01% total harmonic distortion while the Panasonic 100 has 0.5% total harmonic distortion. Problem is, they are both being played through speakers with at best 15% distortion. The only way to "hear" the difference is with an oscilloscope, the human ear can not detect the difference because the weak link is the speaker. Of course, Bose was in the speaker business so consider the source. Listening to him changed my perspective on a lot of things and I now routinely question "conventional wisdom". Because someone says it doesn't make it true.
Anyway, has anyone actually taken a brand new 1/2"-13 tap and measured the torque to run a thread in a piece of 1/2" CRS. Bang the heck out of it next to another tap, then repeat and measure the torque again? If the tap dulls, seems like it would take more torque if it was beat up. I've not done the study, probably should and if it makes a difference I'd put my taps in that Chinese finger trap type of plastic to keep them separated.
I know, that's not what the OP was asking . . . Here are some photos of my "mess".
Bruce
Composite photo of a tool box drawer, loose taps/dies in the bottom one plus a small ACE set
Another drawer (top composite photo) with a couple of sets (4-40 - 1/2 and Metric equivalent) stacked on each other. Some loose metric taps.
Drawer with the majority of my taps/dies. Most are in their factory packaging, but lots of loose ones touching each other also.
Also have a 35-year old Harbor Freight set of 1/4" NC/NF up to 1" NC/NF and an couple of equivalent Greenfield sets in boxes. The HF ones are actually decent!