We take for a given that big projects will go over budget and over time. The core idea of this book is that does not need to be the case. The main reasons given for projects not going according to plan are: bad plans in the first place, making changes as they go along and bad estimations on how long the plans will take to implement. Most of these can be overcome by proper planning.
The core premise is make sure you plan out properly beforehand. Consider the scope of the project and why you want this to be done. If you properly consider the “why” then you won’t want to change it half way through, avoiding one of the largest cause of delays to large projects. The example project for this sort of thing is a kitchen renovation project gone wrong. The owners ended up spending millions on what they planned to be a kitchen renovation but turned into a full home remodel. The main reason was when a complication, such as rotten floorboards, came up they increased the scope instead of trying to find ways for reducing the scope or keeping the roadblock to a minimum
Bad estimations also often derail projects as it gives people a false sense of security in knowing how long the project might take and cost. Oftentimes the estimate is deliberately lowballed to make it more palatable for whoever is paying for the project. The big idea for estimating is to use reference estimation. Instead of thinking of your project as a once off because of all the unique characteristics, instead consider it as one of a group of projects. Not all projects are unique but with enough data then you can compare how long this particular project took compared to all others.
Overall its an interesting book, even if it seems a bit simplistic at times. Sure planning out properly beforehand will help avoid the things you can think of but there’s always some black swan event you haven’t considered that can derail things. I guess if you can avoid as many events as you can then maybe then you might get decent delivery results.