Photo of the watch straps.
This was a project I did to make unbreakable watch straps. The straps are made of webbing, the kind that is used on outdoor gear. The buckle is a link of chain with an opening cut in it.
These watch straps are NOT adjustable. I like to say they are "One Size Fits Me". If you are making your own watch straps, you don’t have to make them adjustable, just make them fit right.
The good thing about these watch straps is they are incredibly strong, and they are easy to take on and off. The bad thing about them is they make the watch sit higher off your wrist than normal. The most difficult thing about the project was getting the strap the exact right length; a tiny bit of error makes a big difference in how it fits.
From a manufacturer’s perspective, making straps adjustable is absolutely necessary. Because then they only have to manufacture one strap, instead of dozens of sizes.
From a user’s perspective, a watch strap does not really need to be adjustable. I put my watch into the same stop on the belt every time. You don’t get any real benefit from adjustability, unless you like to wear it really loose on Monday and really tight on Tuesday.