I've owned maybe a dozen of these at one time or another.
These use the rotating-wedge rangefinder, which is very accurate and shouldn't fall out of calibration unless the camera is damaged.
The intermediate camera is the folding Contina II with the uncoupled rangefinder. This was my introduction to Zeiss Ikon. Mine had a Novar. I eventually bought one (and a number of others) with the Tessar, which is the same lens as on the folding Contessa and the Contaflex I and II.
The folding Contessa always has a Tessar. The early version has a Compur Rapid shutter. The second version has a Synchro Compur. It never used the EV system.
The folding Contessa is a well thought-out camera. It's very easy to use, which is typical of the Hubert Nerwin (the Zeiss Ikon camera designer) approach.
There are many of these on the used market, and I wouldn't buy one that shows physical damage.
I've shot with this quite a bit.
Here's my mini-review of the folding Contessa.
And here's a little shootout I did with the Contessa and the Contarex. The Contessa was no slouch.