Very little in the way of "standard" sizes from my experience in the contracting world. Always bought screws in huge buckets from dedicated fastener supply stores, and the off chance i was stuck in some hardware store, it seemed the available supply was quite random.
screws come in increments of 1/4". (at least in Canada/US)
When I specify screws, I will spec:
screw material type (Steel, galv, hot dip galv, stainless)
gauge
minimum length of threaded embedment
as well as a general note for the maximum the screw is allowed to be shimmed/packed out.
If you don't spec everything you want, you can't be upset when what you imagined isn't provided.