All soils are different. However No dig and diverse cover crops that keep fungi fed and alive are definitely the preferred method as the less the soil disturbance, the more the plants photosynthesise and feed the undisturbed soil microbes like fungi that then build soil carbon and structure.
However for soils with poor structure, low soil carbon, and hard clay pan compaction layers, then subsoil manuring can be a faster option as it gets the food to microbes where it’s most needed. Ideally with minimal inter-layer disturbance, and optionally then with a layer of weed suppressing material, mulching and planting through. You have to always remember to plant out bare mulch and soil however, otherwise mycorrhizal fungi that require plant hosts will die off. About half of mycorrhizae also die within the first month of tilling and a further half every subsequent month soil is left fallow.
When subsoil manuring you have to make sure there is enough soil moisture for the microbes to break down that subsoil manure and integrate it too. Studies suggest materials with a C:N of less than 25:1 appear to be the best to feed those subsoil microbes. Basically anything green, eg. grass, fresh leaves that aren’t allelopathic, or alternatively compost or animal manures if you want a higher bacterial to fungi ratio that the high phosphorus, particularly in animal manures encourages (normally you don’t). Mulch helps maintain moisture, and the mulch should ideally be below a C:N of 100:1 as this speeds the building of soil carbon. Those are mulch materials like leaf mold, straw, shredded newspaper, and ramial (branch) chipped wood, ideally all mixed together for diversity. Those materials that are high in potassium and low in phosphorus are also likely to encourage fungi.
Digging without amending however is generally a bad idea as it destroys soil structure, and can lead to soils drying out where those cracks form, which then causes the soil mucilage (glues) and microbial exudate to dry out and leach. Leaving sand, silt, and clay ready to combine and compact with one another.