Bigger than you can currently imagine. I spent years using sealer and wax before I discovered oils, about 18 months to 2 years ago.
Now every-time I look there are more types of oil to consider, you mentioned Danish Oil, and it's variant, Hard Wax Oil (it's got a wax in it) , or the old favourites boiled Linseed Oil, Teak oil, all these are based on Mineral (highly refined car) oils. But what about Vegetable, Seed (sesame) or nut (Tung, Walnut or Hazelnut) or a fruit oil such as Lemon Oil. Careful, some can go rancid!
Some are Gloss, some Matt and of course some in-between. Some are food safe (that's a whole new discussion), some need a couple of coats some need many.
Personally I'd suggest you start with 2, Danish for a high Gloss finish and Tung or Walnut for a foodsafe (salad bowl) finish. The lessons for the rest can come later.