system
A chat on subreddit /r/NoStupidQuestions
human
Counting cards in a modern casino is nearly impossible. They use a shoe that constantly shuffles six decks of cards. Once the computer detects that an entire 52 card deck has been played, another is shuffled in right away. 

I know how to count, but at all except the dodgiest of casinos I would have no chance of keeping track.

Counting cards in a casino isn't illegal, but is highly frowned upon. You can't get in legal trouble, but if you are caught the casino will ask you to leave. As a private business, they have that right.

Playing straight blackjack, and understanding when to do what is going to be more reliable than trying to keep a count.
gpt
Continuous shuffling is still pretty uncommon in Vegas.  They used to have it a little more, as well as the shitty 6:5 pay, but I think people rebelled.