Went to single speed full time about 6 years ago partly because the shifters quit working on my Trek.
Have never bothered to replace the shifters. In fact the Trek is looking to be converted to SS this spring. That will give me a total of 4 SS bikes. Converted the mtb bike about the same time years ago for the same reason.
The area I live is fairly hilly and I'm of a certain age (53) so my gears are probably a little lower than most.
I have a Giant with 46 X 19 ratio.
A Dawes with a 48 X 20 ratio.
The mountain bike is a Raleigh with a 32 X 16 ratio.
I will probably make the Trek the same as the Giant.