You are right. I did mean to write six or twelve. Thank you very much for spotting the typo and pointing it out.

What matters is that in order to determine the insured salary, one counts backwards from the end of employment, not from the moment of application. More precisely, the most recent six (or twelve) months of employment within the two years preceding the application are considered.

In other words, gaps between jobs have (almost) no negative effect on the insured salary if one has contributed long enough overall.