I’ve heard people say that the bracha of shehakol covers all foods. Is this true?

I've heard some people say that the bracha of  Shehakol covers all foods. So if one doesn't know   what bracha to make, one just says the bracha  Shehakol. Is that correct? It's a little bit   more complicated than that. The Mishna says  that if one does say Shehakol on any food,   it does cover that food. However, the Poskim  explain that this is only b'dieved, which means   after the fact. So if one accidentally made  a Shehakol and picked up an apple, it's not a   bracha levatala. You can eat the apple. But of  course, a person should say the proper bracha,   Ha'etz. What if one doesn't know the proper  bracha? Then one should go ask. They should not   make a Shehakol if they don't know the bracha.  If it can't be determined what the bracha is,   even after researching it, and there are cases  that are brought where we make a Shehakol because   this is a doubt to everybody, for instance,  the Shulachan Aruch discusses what bracha   does one make on cane sugar? Is it Ha'adamah  because it grows from the ground, sugar cane,   or there are even those who say it's Ha'etz.  So, the Shulchan Aruch says because there are   different opinions, and there are those that say  it's Shehakol, therefore the proper bracha to make   is Shehakol. Whenever we have a doubt, we make  a Shehakol, but the doubt means a real doubt,   that it can't be determined. If just I don't  know what bracha it is, then I'm supposed to   go ask. If I didn't ask, and I did make the  Shehakol on it, then I could eat the food.