My experience (pre-resin, pre- synthetics) was similar to Avabob's recollection (we are in the same age bracket). One exception though. During the lacquer era (1960s), and prior to walls and lane blocking, conditions were usually very tough, with few exceptions. Stringing strikes was hard to come by. In a few instances, the lane track could produce high scores, but in my neck of the woods, this was a rarity. Nobody, and I mean nobody, averaged north of 205 and the few that did, they were the absolute best in the entire region. I am talking about some really good players too. With the advent of polyurethane coatings (circa 1973), proprietors could no longer oil the lanes the way they did on lacquer. Oil got pushed down the lane, causing an epidemic of out-of-ranges. Balls "rooster-tailed". In 1977, that changed. The ABC basically threw its hands up, and that started the "wall" epidemic. Scores and averages began to dramatically rise--- overnight too. From that point on, the typical "house shot" has resulted in a flood of oil in the middle, with lots of friction out to the edges. Back in the 1960's, we oiled the lanes from gutter to gutter (with a spray can). There was no help to the right and no "hold" in the middle.
I remember a quote from a PBA Hall of Famer. He said that anybody who shoots an 800 series had "help". I maintain the same logic could easily apply to anybody who claims to have averaged 220 in the 1960s. If they did average 220, they had "help" too. Some proprietor was walling up the lanes (illegally). Otherwise, that type of average would have been next to impossible to achieve back then.