I've been sewing & crocheting since I was a little girl. My grandmother taught me how to do both.
Usually, when I sew, I make costumes -- simple costumes for Ren Faire or historical costumes for balls. For example, for Dickens Fair last Christmas, I made a complete Victorian outfit which involved a 5-gore skirt, blouse, waist belt, Spanish bolero jacket, and a faux-fur muff.
Luckily, I already had all of the underpinnings for this outfit, or I would have made them too. Consequently, this was a "simple" project that only took about one month to complete, which including drafting a pattern, making several mockups, and then sewing.
My most complicated project took over 6 months of consistent sewing & fittings 3-4 nights a week (which was for an 18th century gown, complete with panniers, multiple skirts, underpinnings (18thc corset, bloomers, and chemise), and accessories (including building a wig)
Is it any reason why I really enjoy knitting? Most of my knitting projects can be finished in under two weeks and is *easily* portable. Bringing an 8 yard cartridge pleated skirt to hem on your lunch break isn't exactly feasible.
Not that all of my sewing projects are complicated. I can easily make small singular things, like a Ditty Bag in under 20 minutes or catnip mice in about 5 minutes, which is why I mostly don't knit "bags" or purses -- mostly because it's "sew" much easier to make them out of fabric. Heh
This is also the reason why I tend not to sew my own clothing (i.e every day clothing). It's usually faster & cheaper for me to purchase commercial clothing than it is to make it .....unless it's a super unique piece or costs WAAAY too much money to justify buying it (i.e. $300 for a dress).
Just like knitting, I much prefer to use my time to make something 'special' and unique that is going to show off my talents & hardwork, and that is fun & enjoyable for me to make.