Because I like a longish leg on my socks, I generally knit 80-85 rows after the cuff. When I’m using 100 gm. balls there’s no problem having enough patterned yarn for the foot. But, with a 50 gm. ball it’s a different story. A pair of socks takes 100 gm. of yarn (often with enough left over for a pair of legs). A 50 gm. ball, plus another 50 gm. ball of a contrasting solid gives me a pair of socks, but it takes some fiddling to extend the pattern yarn well into the foot.
First of all, I unwind the ball, find the centre, cut, then roll up 2 smaller balls. That way I know precisely how much I have to play with for one sock. With this pair I didn’t get as far into the instep as I wanted so I extended the pattern yarn by alternating rows with the contrasting solid. I had no patterned yarn left when these socks were done!
I still prefer working with 50 gm. balls of patterned yarn when I can get them ( they’re getting harder and harder to come by) because a finished pair costs considerably less than the larger balls (even counting the second set of legs I get from them).