The challenges with the post's suggestion are (1) it accounts only for the time of the person needing information, not the one providing it, and (2) a specific question takes a small time to answer, but pre-documenting everything that is needed to answer any question takes orders of magnitude more time.

Some of this is outlined in Snowden's (not that Snowden) Laws of Knowledge Management.

http://www.gurteen.com/gurteen/gurteen.nsf/id/km-seven-princ...

These two are especially relevant:

2. We only know what we know when we need to know it.

7. We always know more than we can say, and we always say more than we can write down.