I have a 3 player 6 character group going, average time per scenario is 1:15 and thats with all the chit chat that goes along with hanging out with friends.
A lot is the luck of the draw, and true planning in trying to corner the villain or focusing on the objective at hand and not just mining for better gear, which tends to happen early on in each adventure.
And yes Mummies traders added a whole different time consuming monster into the mix
Also never be afraid to explore even if you only have 1 card in hand, there are other players there to take the load off you. Cant even count how many check to defeat 20+ ive taken down with d4s.
Also not the first option, but if you feel your lacking the dice, you always have the option for the additional d6 if you discard. Ive seen Rooboo fully decked out, and shes a very strong and fun character.