Some lines are easier than others to trace.There are books written on my DUNHAM, FREEMAN, HINCKLEY, STARK, and other families.Also, the early New England records are the best in the country, probably resulting from their early emphasis on good schools[with some exceptions, as you've found].
I don't think some dropped or added the c.I think the record keeper just wrote the name the way he thought it should be and the people were too polite to criticize or correct.
I've been working on family history for thirty-five years, but I haven't been retired that long to devote time to the hobby.I'm in South Dakota, and I'm often amused by people who write for online advice saying they do not have access to many records.They should have started when I did with self-addressed stamped envelopes and long waits at the libraries to receive one microfilm.That did make us aware that we needed to document the direct line for ourselves, though.Nowadays, these young whipper-snappers complain if they are not handed proof on a silver platter.
Do you include George BUSH and Barack OBAMA among your hard-working honest people in the HINCKLEY family?--just checking.:-)