There will always be uncertainty that something could deter you from your ambitious goal of no delays. You still need to plan for that.
But, if your mentality assumes that something is going to cause a delay and therefore you shouldn’t set an ambitious goal, internally, you are just leaving opportunity on the table.
The point isn’t to rush things. You still need to plan, give the project enough time to be executed effectively, and allow for realistic timeframes. But if you’re mentality assumes there will be a delay, you are much more likely to allow it to happen.