Most of my workshop is populated with stuff that I value, but in the cold light of day, is worthless: nails are a case in point, as are slotted head screws. Dad left me boxes, I sorted them, put them in trays and there they sat for 20 years. If I needed a screw I bought modern ones with cross head, Torx or allen head...so all the old ones have gone as scrap.
When I inherited my father-in-law's workshop, one of my most treasured discoveries was his stock of proper brass slot-headed screws. Solid top-quality brass, not the ridiculous nonsense you get in DIY stores these days. Over the years, the stock is slowly dwindling, but each use for one has to earn its right to be worthy of one of the screws, invariably in hardwood. Each hole carefully pile-drilled in two stages, countersunk, and the screw coated in beeswax before insertion.