‘Hang Loose’ is supposed to give multishot 5% attack speed and a 5% chance to give you haste when you use or proc multishot. It maxes out at 3 points with 15% atk speed and 15% chance of haste.
In practice it triggers way more often than it should. It’s so significant I’d have to be ridiculously lucky for it to be a coincidence.
With the base 5 arrow multishot I counted 7 times out of 30 I did NOT get haste.
On a character with +8 arrows for a total of 13 it was only 2/30.
Both tests were with 3 points in Hang Loose. These results seem roughly consistent with what the probability should be if it rolled an extra time for each arrow you shoot.
On the off chance this is intended behaviour and all my efforts spent testing were wasted the tooltip for the passive needs to be updated.