How far back do you look at a player's stats?

[viper]

Now that we have worked our way about 35 days into the season, I am wondering how people view older stats.

For hitters you can look at YTD but generally, sites let you see last 7, last 14 and last 21 worth of stats. Players are streaky but they tend towards certain numbers. Still, if a marginal player had a super great first week and has been a dud recently, it may be time to go in another direction. I tend to look closely to projected stats and to the last 21 days. I try not to view YTD at this early time.

For pitchers, for several years I have tracked my staffs last five starts fairly closely. Of course, in the past at least half my leagues had benches. This year none of my leagues have benches and the FA starters are from starvation for the most part. My decisions are keep them or cut them replacing them with a quality MR - which are readily available. However, IP replaces Ks in 3 of my 4 leagues, so that option has obvious drawbacks. I am curious how others view SP in their decision making process.