I use parking on my HAED designs too - I found it difficult at first but now I wouldnt use anything else. There are some great videos on You Tube on how to park. Thats how I learnt. I love watching Floss Tube on YouTube which is basically lots of stitchers posting about their work, what theyve bought, advice on stands and different threads/techniques etc. You really can learn a lot and its fun to watch too :D
I admit you have to get used to parking, but when youre used to it, its great! Work from the top of your project (left or right top corner) down, so the threads will hang at the bottom. If there are a lot of threads you can use a hairpin to keep them together and not create a mess with knots.
While parking is a great technique for most patterns there are some where it just isnt as applicable. The pattern Im stitching at the moment is huge with lots of minute changes in color. When I considered how it would be to sew using parking, not only would I have to have 30-50 some threads going at any one time, but the waste of thread would be extreme as there was often a lot of space between stitches. It was just easier to follow colors one at the time and go where they were going, which believe me was in no way straight up and down.