Hi, and welcome to our Knitting Family!
To comment on your question of tension (with any particular yarn): if you are making your own pattern like for this Lion Homespun scarf...a good clue for the right needle size for a yarn is the recommended needle size on the label of the skein. Start there. Knit a swatch (trial square 4"x4"). If you like the 'tension', pull out the swatch and begin knitting the real deal. If you don't...pull it out and use a bigger (or smaller) needle and re-swatch. If you think you'll be using the yarn again and again, save your swatches with a note pinned to them saying what size needle it took. Keep your swatches in your knitter's notebook. (yes, start a notebook) Swatching is an unavoidable part of a knitter's life!
In my opinion, your scarf dimensions turned out perfectly!
I like a scarf that is skinnier but longer. 4"-5" is my favorite widths. Six inches gets unmanageable around the neck. Especially if the yarn is heavy.