I'm trying to crochet a scarf and need some advice

[Tansy_Gold]

2. Great minds think alike!

It may not be orthodox, but I do the same thing: Try it both ways (or more, if needed!) with a small sample to find out which makes a better fit. Your individual hand, how tightly you crochet each stitch, will affect the length you need on that turning stitch. Also, what I've found, is that my tension of the yarn can increase or decrease between the chain stitches at the beginning of a row and the double or treble stitches of the pattern, if that makes sense.

The same will sometimes be true of the number of chain sts needed to turn a corner. It all depends on the weight of the yarn, the pattern, etc.