scale count sexing

[rwg]

Hello,

My corn just shed for the first time in our care (about 1 month after her last shed in the pet store just before we got her). I read a method of sexing that involved counting ventral scale rows from the cloaca to the tail tip. less than 130 is probably a girl. More than 140 is (likely) a boy. In between is a toss-up. Well, I didn't count too accurately...pretty small scales at the tip, but it's certainly no more than 100, so it's a girl I assume.

A couple questions. I assume that since this method made no reference to the age of the snake that snakes have the same number of scales all their life. Is this true? How reliable is the scale count method? We had already decided she was likely a girl from her tail shape, and the pictures in the corn snake manual.

Also, how accurate does her shed length correlate to her actual length? I've wanted to measure her but it's hard to get her straightened out to get an accurate reading. I'm a bit nervous about being rough with her. Is the shed going to be longer or shorter than the snake?

Thanks.