I WANT to do what Elly does, or follow Mo's suggestion. I just lack the focus.
I usually can't figure out what I want/need until the season is upon me. And usually a bit into the season so I have had a chance to actually wear what I have and figure out what I need. I know, I know, but there is the truth.
So, I tend to want to update later in the season. I want to get better about this, but have yet to formulate a strategy that works for me.
Also, fall/winter is my dominate season. Spring is usually 4 weeks or less. Summer comes in mid June and is usually gone by early September. Because of how long winter is for me, I usually do a winter refresh while everyone else is buying for my all but non-existent spring.