I not afraid to wing it. (Except for reactive ingredients when baking)
But as a guideline 3 whole to 1 ground is close enough for Govt work. Peppercorns, Cumin Seed, Mustard Seed, etc. If I'm doing a recipe frequently I'll gram it out and refine it.
I do pay attention to ratio's, i.e. recipe calls for a 1T of salt, 1 T of whole cumin - I know that I don't want close to 1:1 ratio but 3:1 is reasonable. So I may use 1t of ground. If spice mixture is overwhelmingly cumin smelling I might revisit other ingredients.
A big fail I've seen at Italian places is measuring cheese by volume. I've literally had this conversation: Yes I know that's what the recipe calls for but 1C of grated parm is not the same amount as 1C of snowflake parm. Yes you can insist it's all 1C but one weighs 200g and the other weighs 400g. Which has more cheese? NO! It's not the same! ( No wonder cooks drink too much.)
Seasoning with herbs / spices is not an exact science. Think about what you like, what goes well together, and go from there. Don't be afraid to fail and if you do remember why. And always do your S&P 10:1 by grams.