When I was in there were three "classes" of dubs.
The "true believers" constituted a small minority, probably about 20% in the typical congo. These were the super zealous or self righteous among us, although often respected by the rest of the group.
About 30% fell into the "walking wounded" category, meaning they were troubled souls with many problems, often but not always of their own making, and they were likely to hang on firmly to their membership because of the perceived long term health benefits (the promised perfection). As for the body of JW doctrine, most of them just didn't know what it was since they seldom read the dispatches. They knew what they were taught when they first started and rarely progressed from there.
That left another 30% somewhere in the middle, matching your description of doing "just enough" and maintaining their social circle and family or business ties, but clearly not intellectually committed. They paid lip service to but were often flexible in their support of many JW rules.
Obviously, the percentages are estimates and there's some overlap between groups. But I came to think this was pretty universal, at least in the U.S.