Data granularity: get_network_difficulty vs get_network_hashrate

[PlebeiusGaragicus]

Pulling one year of data from both of these functions returns interesting results:

get_network_hashrate( ) returns a single data point per day - 366 data points
yet, get_network_difficulty( ) returns two data points per day - 730 data points

Is this the correct granularity to return? Network difficulty changes once every ~2 weeks yet network hashrate estimates changes with every new block. I was expecting these functions to return the reverse case.