Greetings,
@Despoina! Your question particularly resonates with me, as I am only fairly recently beginning to study, learn and apply flourishes to my Spencerian practice.
I will, however, offer my standard disclaimer: I’m no expert on the topic and still consider myself very much a beginner, so take the following as on the order of opinion. And, let’s see, oh yeah, “Your mileage may vary.”
I recently completed Suzanne Cunningham’s “The Art of the Oval” four-session class on flourishing. Her first session went over the handout, “Rules, Rules, Rules” and presented 12 of them. Her instruction to us was that they all apply equally to Spencerian.
That said, she demonstrated everything on Copperplate script. Since I haven’t learned that, it was clear that certain of the many flourishes just would not work in the same way on certain Spencerian letters. But then, a big takeaway from the classes is that there are TONS of ways to make flourishes and generate your very own ideas even though certain “rules” (I like the term “guidelines”) apply.
I’ve fairly regularly run into the metaphor, “there are no calligraphy police watching your moves/work” here at the Flourish Forum as well as in Suzanne’s very class! Beauty is in the eye of the beholder, and for me, especially with flourishes, this seems to be very true. Aesthetic beauty will be experienced differently for each of us. Oh, and Platt Rogers Spencer, himself, welcomed individuality in the writing of his eponymous script! Can’t find the quote for you at the moment, but trust me.
What is working for me is to look at a lot of examples of calligraphy and Spencerian script — both historical as well as by contemporary adepts. While there may be a lot of similarities and “repeats,” very quickly one finds that flourishes and OP, in general, spans a wide spectrum of expression! From these examples, I’m discovering my own style and “density” preferences which is informing my practice and performance.