I have learnt that calligraphy is not a part-time job or hobby. One has to work very hard to be a calligrapher. One of my teachers favorite saying is that one should work 30 hours per day if one wants to be a calligrapher.
When you look at a writing of thuluth script, you will notice invisible lines going in a certain angle that have measurements, like 5 dots or 10 dots. Zakariya hoca said, “these relationships of dimensions are only the beginning of writing.” Therefore, when you are first learning how to write in Arabic calligraphy, you are learning the measurements of letters.