so much / so often / so many — used mainly in negative sentences (e.g. 'not that often'). Often appears in the pattern 'そうそう〜ない'.
彼はそうそう仕事を休まない。
He doesn't take time off work that often.
そんなミスはそうそう起きないだろう。
That kind of mistake probably won't happen very often.
その店は評判だが、値段はそうそう安くない。
The shop has a good reputation, but the prices aren't that cheap.
oh yes!; that's it! — an interjection used when remembering something.
そうそう、昨日の約束だけど、時間を変えられる？
Oh right — about yesterday's appointment, can we change the time?
そうそう、財布を忘れてた！
Oh yes — I forgot my wallet!
that's right; exactly — an interjection expressing agreement or affirmation.
A: 彼の説明は簡潔でわかりやすい。 B: そうそう、図も良かったね。
A: His explanation was concise and easy to understand. B: That's right — the diagrams were good too.
そうそう、それが問題なんです。
Exactly — that's the problem.