I am wondering if SS2 is predominantly for high stakes games or if it applies to low stakes games as well. By low stakes anything from 1/2 limit to 5-10 limit.

Thanks.

Mid and High limit advice, IMHO.

Doyle's NL style is predicated on large semibluffs, image, etc. If your opponents are too dumb to lay down a hand, you'll be gambling with the worst of it. He addresses this, but doesn't show you how to outplay weak opponents, the knowledge of playing straightforward is assumed.

PLO also offers looser-than-typical advice, so you need some reading ability and quality fundamental postflop play. Loose players will really up your variance more than your winrate (though help both) using SS2's advice.

Limit preaches controlled aggression; it's not tailored to small stakes (for example, nothing on raising for value with nut flush draw and 5 probable callers, stuff like that), and is aggressive with middle pair from the blinds, etc. It's solid for all levels, but there's a lot of ways to extract extra profit from weak games that does not get covered.

Most other game chapters follow this advice line, too. Give you tools for success at middle and higher levels, assume you know how to play, don't cover situations that only occur in loose games or concepts that come out in such games.