I didn't click the blog link because the OP could have listed the contents on here if a discussion were the actual goal.
Maybe its mentioned in the blog,, or maybe its in the wedge bag that's used, but a quick link is important.
I mention a quick link since some newer cyclists might read thru a more basic thread like this.
Tube/tire issues is probably the most common mechanical when riding(so spare tube and boot). Next is probably adjusting something(so multitool)- saddle height/angle, stem, bar angle, lever straightness- since things shift and loosen with use or when a bike falls. After that, I would figure a chain issue is the next most common. Having a matching speed quick link can be helpful and it takes up no measurable room.
Again, this may be addressed in the blog, but hasn't been mentioned yet in the thread.