I guess it depends what one considers veg. There's the seedling stage and veg. stage. Mine kind of run together, gray and blurry, Lol. I have never gone into flower later than 6 weeks from seed, and usually more like 5, and occasionally 4.5ish with a spectacular start. So technically, I'm only true vegging for a week or 2 if one considers the 1st month to be seedling stage.
Also, when you run multiple strains from seed...they don't all grow at the same rate, some are more advanced that others going into flower. I also always run one 'mystery' seed from somebody's bag of high end weed. So I have a plant with unknown genetics. I enjoy the challenge of figuring out what to do with it. You can take a schwag seed and turn it into something good, so you can take a rogue seed out of a high end expensive bag (likely a selfed seed) and definitely get something good, sometimes outstanding.
If I truly vegged for a month...I would have less control, plants would be too big and I'd have to use hormones to freeze the size. And even with hormones, they still stretch an inch or two or three.
This is, after all, a useful hobby...just for me. I don't sell weed, I give excess away to my inner circle of friends who in turn find me seeds from the world over. Some of my friends do a lot of traveling.