The idea that local events always determine the validation of a destination is a bit too absolute; there is a middle ground.
It is true that events like the Grand Magal can transform a region, but for a business traveler to Dakar, for example, the impact is marginal if they do not plan to attend.
Flexibility and adaptability are more important than considering every event as an absolute obstacle, because solutions to bypass constraints can often be found.
For example, staying in a neighboring city or a less central district during a big festival can offer an equally rich experience at a much lower cost.