There are no shallows in philosophy, no knee-deep, shoreline waters. It is abysmal from horizon to horizon.
Nothing we read will be textbook-like. That is, nothing we read will begin easy, with starters, and proceed gradually through middling difficult intermediates, and on to truly difficult finalities. So you will not likely get better as you read straight ahead. You get better backtracking, as you re-read: the intermediates come into view on a second or third reading; the finalities only after long frequentation, sometimes life-long re-readings. (You must learn to cultivate the pleasures while overcoming the challenges of re-reading!) Re-reading is the analog, in reading philosophy, of working through a textbook.
To make progress in philosophy, you need a high confusion threshold. You have to be capable of being, willing to be, thoroughly confused without falling into despair. And you have to be willing to enter into confusion again and again, even while not seeing any exit from it. The exit, if there is one, is always “across a step or two of dubious twilight” (to borrow a phrase from Robert Browning). No one who refuses to enter, or who will make no settlement in that twilight, that confusion, will ever be a philosopher.