Raglan sweater.. pick up or cast on?!

Hello!
I’m beginner knitter, I’m interesting in raglan sweater and knitting in round.
I ask for the better in knitting sleeves: pick up stitches from underarm or cast on stitches on needles? what do you prefer?!
I have another question: some patterns say that we must cast on some stitches after we put sleeves in stitch holder, others say not this! I’m confused!
Best regards.

((I so sorry for language! ))

On a top-down raglan sweater, you should be doing both. (Or could be. Some people seam their underarms.)

You’d cast on stitches for the underarm at the time you’re placing the sleeve stitches on holders, then when you go back to do the sleeves, you pick up and knit those cast on stitches to make a bottom strip to the sleeve and connect it to the body.

Casting on adds the side of the sweater - a panel of stitches between the front and back if you will. I can’t imagine a good top-down raglan pattern wouldn’t call for casting on stitches after you put the sleeves on stitch holders. The number cast on affects the fit of the armhole and ease.

:cheering:
Thank you so much :muah: