I figure the correct technique is the one you like best and that gives you a good finished product. I ch1 between the groupings of 3dc and I always ch3 in the corners.

Aside, from granny squares or motifs, one thing I do differently than every book or pattern I have seen (for a project that requires crocheting back and forth) is at the beginning of each row and after the turning chain is made, I make my next stitch in the base of the turning chain. It produces a firm, straight edge, much more so than the usual method. I still count the turning chain as the first stitch and at the end of the row I have a firm stitch below to make my last stitch. It produces the look of a selvage and makes sewing pieces together so much easier. I know it's not "correct" but I prefer the look. So don't be afraid to break the rules an have fun experimenting. After all, isn't that what designers do?