yemek is an example of a Turkish transitive verb which demands a visible object in the sentence. If you don´t have anything else in your mind, you just add yemek ´food´. I have also noticed yazı yazmak somewhere but I can´t find it any more to check what was really ment by it. Are the Turkish verbs very strict about their transitive/intransitive quality or is this just a coincidence? Can you just read, sing, cook, draw and listen without mentioning the object?

                   Barış Bey oturma odasında (gazete) okuyor.

And vice versa, can a usually intransitive verb take an object occasionally?

                   Ayşe hanım tüm yolu yürüyor mu?

In Turkish, a verb is either transitive or intransitive but not both like in English.

I stopped = Durdum

I stopped the car = (Arabayı) Durdurdum

So it makes it possible to drop the object of a transitive verb when it is clear because of a context.

(Onu) gördüm = I saw it

(Onu) biliyorum = I know (it)

(Onu) durdurdum = I stopped it

(Onu) taşıttım = I have it carried

(Onu) indirdim = I took it down

(Onu) ufalttım = I made it smaller

Your "yürümek" example seems like a contradiction. I think it was a transitive verb actually (in old times) and yol is so obvious as an object that it may have been drooped as a result as described above over time.