Probably an average per week will be ok but if not possible then the month is also OK - those who've been on the chain for years will probably need historic figures and values if they earned an amount above the capital gains threshold and didn't power down.
In the UK, we need to know the fiat price of crypto at the time of receipt, even if we didn't pay for it - called "fair market value". So with staking, that becomes important even though there's nothing specifically mentioned in our government tax guidelines, better to take the conservative approach! Say your stake grows by 10 HIVE per day through staking and you have 100k HIVE, when it comes to selling it, you need to account for how you got that extra 10 HIVE if you haven't bought it. It's a minefield!
As it's all HIVE, we'd only get taxed when it comes to exchanging HIVE for another crypto or fiat in the UK, I don't know how it works in other countries. So earning purely in HP wouldn't be a taxable event, converting HBD to HIVE would be, powering down wouldn't be... as far as I know.
Also I'm not a tax consultant/accountant, I've just studied the topic and this is my understanding so far so!