My experience in practicing calligraphy for more than 50 years is that regular script is completely derived from official script, which can be said to be the basic skill of regular script, while regular script is the basic skill of writing all kinds of running scripts and cursive scripts.
Although seal script is a pen heart, isn't it an official script?
So, I think:
1, most strokes and strokes of seal script are completely different from those of regular script;
2. Many strokes of seal script are completely different from regular script in structure and word formation, which is difficult to identify and remember and wastes time for no reason;
Therefore, I advocate starting with official script and then learning regular script; Regular script should start from Liu Gongquan and then learn from Yan Zhenqing. I make the fastest progress by teaching students like this.
I hope my answer is helpful to you.