On drawing up the watchlist for the week

Bit of a rookie question for the vets out there, but when you're looking at the charts on a Sunday evening, sifting through hundreds of tickers, how do you guys decide what makes the cut for your watchlist? I'm finding myself putting way too many on there, then feeling overwhelmed come Monday morning. Is it purely about identifiable patterns or do you have a specific sector focus week-to-week?