I tried to beat all of the missions the fastest i can. It seems i did it under 2 hours, however there are lot of collision with other chiefs, but it seems that don't mean many time losing. I had luck in the mission "Tam in a Jam" i barely lived through that many shooting by those irish gangsters. And maybe i losing some times when i did a visit into Harry's weapon shop, but that was deliberate, because i shopping myself with lot of weapons, and i could beat faster the shooting missions (and the last mission, thanks for the grenade).