i only check chart for 24hr/48hr,  and follow with increase of difficulty, and then i can feel certain , the hash rate is same or little up/down and/or number of finding a block by chance is decreasing or increase.

7day only gives u other thinking process, like average hash.

edit: i think i mislead people, into thinking 42th is the real live hash,  sorry, its not real hash guys, its based on block found , etc