My grandmother, who was a professional seamstress with her own business, insisted I learn to sew from the age of eight. By age 13, with her guidance, I made my first entire suit, a yellow suit with white trim, jacket and skirt. I've been making clothes ever since, and that's been decades. I've also designed a lot of clothing and done some tailoring.
Over 20 years ago, I took up quilting and have not sewn much clothing since. I thought quilting would be easy, given my sewing skills. I soon found out it is different, requiring much more precision than clothing. I have successfully done some patterns requiring accuracy to 1/32 of an inch in both the cutting and piecing. I now prefer quilting but do still make some clothes.
It's not that the 5/8 inch seam seems big to me, it's that the 1/4 inch seam seems small, since I learned sewing first.
For the person that warned about sizes on patterns, here's a way around that: Get the closest sizes to your measurements, lay out the pattern on the straigt of grain of fabric, measure each part of you and then that part on the pattern, extend the pattern with chalk lines if necessary (or reduce it), and cut on the chalk lines.