The cheapest version: the impact of local events is not always the decisive factor we imagine.
You can often adjust a trip with minimal changes to avoid most inconveniences.
Shifting a few days or choosing slightly more distant accommodation can suffice to bypass high costs and crowds.
For example, visiting Amsterdam during King's Day would be chaotic, but it is easy to come a week before or after to enjoy the museums at a lighter price.
It is a low-energy approach that saves research and stress.