I've owned 10 Shiro's and presently have 8. Out of those only my two 100NS Tabargans (one sadly sold) and my Quantum Ursus NL (not so sadly sold) were drop-shut out of the box. Of course the Tabargans have sliding bar, AXIS-type locks and drop like Benchmades. The QUNL had the best out-of-box action of any Shiro I've handled and was also the sharpest on receipt.
My Hati is old school on washers and never has, nor I expect never will by nature, be drop shut despite considerable work as I bought it well-used in not great shape. I have but one F3, an earlier Gen, that I've also put a lot of work into, successfully solving a lock-up issue, that doesn't want to drop shut though it will shake down with a little wrist.
Of the rest, my four that drop shut are my NeOn UL--obviously a small--the 111 CF (2nd Gen?), and my two F95's. The Turtle is SRBS, probably Gen 2, and the other is an R Series MRBS (what used to be known as a Three Bears). None of those four were drop-shut out of the box and benefitted from tuning and break-in. Tuning includes complete disassembly, soaking all parts in alcohol, getting all the grease out (yuk), polishing all interior surfaces, de-burring the bearing cages, then reassembling with W10 NanoOil for a lube. I never thread-lock pivots unless they constantly loosen, and run my Shiro pivots just thumb-nail tight. That keeps those knives centered and free-dropping and if they drift a little over time I just bring them back with no tool needed.
The 111 is an absolute thumb guillotine and both F95's have a nicely damped, hydraulic free-drop. The pivots stay cleaner run dry but the light lube helps the action and they feel a little smoother in both directions.