It wasn't that I was planning for particular times, though I suppose I could lie and look all organized and such. Really my knitting is deadline based, not seasonally based. I work on commissions as they're requested. When I work on personal things I have so many that I have yarn for that I generally just blindly grab yarn and check my list to see what it's for before starting.
My stash is organized into three sections. The first section is customer related. It's all numbered and waiting for it's turn. Then there's a box of yarn that I know exactly what pattern it'll be for. I keep a list of how that matches up in Word. When new yarn comes in I hit up Ravelry and hunt down it's pattern, so that it doesn't get relegated to the Bin. The Bin is random yarn that I have no real idea of what's going to happen to it, it's just there.
So my knitting could be shawls, gloves, hats, whatever depending on what's been ordered or what I've grabbed from the box. I knit for people living much further north. I knit for people living further south. I knit because I have yarn on hand. Special occasions often get a line jump pass, like for Kid's birthday mitts. Perhaps when I knit up all the yarn I have on hand I'll start planning my knitting to be more seasonal.
I still only work on the Lagoon afghan in the winter time though. That much yarn on my lap in Texas heat? Insane. I may be off my rocker at times but I'm still sane enough to recognize that.