What do you mean perpetual calendars should be avoided?

Easy in the calendar: suitable for doing … or should do …

Avoid: it is considered inappropriate, but it should be avoided.

For example, the calendar on September 6, 20 14 shows:

Appropriate: marriage, sacrifice, blessing, migration, etc. It is suitable for marriage and marriage; Sacrifice ancestors and gods; Move, move, etc.

Taboo: Winning the lottery (accepting bride price) and forming an alliance (small sworn brothers, big strike and reaching an agreement) are taboo, otherwise things will happen.

It backfired.