You have kind of answered your own question, in that, because there are such a wide variety of plants, often sharing the same soil area, there isn't really a general guideline for herb garden fertilization. It would probably be best to first focus on the soil, like a good potting mix for containers, and regular additions of organic material (think compost, aged manure, leaf mold, Leaf-gro) to in-ground herb areas.
Next, a soil test is a good idea to know how rich in nutrients and minerals your soil already is, which can affect what to do as well. They can contact us any time for this information, but a link is usually right on our home webpage. Here is that link, and if you'll notice, there also is a link to regional labs which can complete the testing.
https://extension.umd.edu/hgic/soils/soil-testing
It might make sense to divide herbs into groups with similar needs and growing conditions, for instance, those with small leaves that grow natively in the Mediterranian area usually are used to dry, relatively infertile soils.
The following is what one of our texts (Ortho All About Herbs) has to say on the subject:
"Although most herbs don't need as much fert. as heavy-feeding veggies, they respond to moderate periodic applications. The amount and frequency depend on the inherent fertility of the soil, whether it is clay or sand, the length of the growing season, and how severely you are cutting back the herbs. As a general rule, light monthly applications of liquid fert. should suffice to maintain good foliage color and an acceptable rate of growth. Overfertilized with nitrogen, herbs will make rapid, lush growth, but will not develop as intense a concentration of the essential oils that give them their characteristic flavor. Large vigorous plants with broad or numerous leaves can use more fert than small, wiry, slow-growing herbs."