I didn't talk of 7 days, but yes you are right . It is a really big confusion the activity system, maybe less time we are thinking of it and less trouble we will have.
Looked like it
31 weeks * 14 points = 434 activity points.
From the first of march 2014 to 11 of may 2015 : 436 days ... 434 days (his activity) / 14 activity points = 31 weeks Maybe I can't explain my thought.
I might be wrong but it is actually 62 weeks as 14 days is 2 weeks not 1 week.
Yes , sorry I was wrong and I meant 31 activity 'times' ( each "activity time" is 14 days , so two weeks). Thanks for your correction.