Importance of a tripod

It seems that I was very lucky with my first shoot for my panoramas as my tipod had a spirit level and without thinking about it, I used it and ended up with straight images. Looking at some of the other work in the group, I can see that people have struggled with having a wonkey tripod. This is a huge issue as it creates photos that are not level.
If your tripod goes up and then back down around your panorama, it becomes a nightmare to stitch together and normally results in a large amount of the photo having to be cut off. Here is a diagram I have drawn to show how uneven photos causes you to have to cut and crop large parts off of your panorama.The black lines are to represent where you would need to crop this panorama.

And here is a diagram I have drawn to show how much more of the image you can keep when your tripod is flat.

Because of how much data you could lose by having a slightly uneven tripod, I have realised that I will need to continue using the spirit level on my tripod to insure that the images will be as flat and inline as possible.