That is awesome news, congrats! CLIs don't have to be insane amounts, but every little bit will help. I imagine if you had more utility with it, they would be more generous, but still great to see 800 -> 4,800 in a year. I always recommend avoiding HP CLIs unless absolutely necessary, and Discover will tell you if it will be a SP or HP.
They like to be one of your only cards
Where are you getting this from? They're one of many cards for me and I've had no problems getting CLI's to the point where my Discover it is one of my highest limit cards.
Be careful assuming such trends.
I imagine if you had more utility with it, they would be more generous
Don't rely on the usage meme. My Discover it and a number of other cards with significant CLI's have seen little to no use. It is not just about usage. It is not just about the account itself. One's entire credit profile matters.
Congrats on your approval.