The eight days Machame variation is the ideal schedule for this route. On the 7 day Machame route, the trek from Barranco to Barafu is broken up into two days, allowing for a short day just prior to the summit attempt. This is important because summit day begins very early, around midnight, so climbers are sleep deprived going into the toughest day on the mountain. By having a short day beforehand, climbers can be better rested.
The 8 days Machame route is highly recommended and used by most prominent Kilimanjaro operators.