Why high cards are less likely to follow high cards.
Suppose that you are using the High-Low count, according to which 10, J, Q, K and A are high cards. There are 20 of them in a 52-card single deck. The probability that the first card dealt after the shuffle is a hign card is 20/52. The burn card must be ignored and treated as one of the 52 cards to be dealt if it is dealt face down into the discard tray and not revealed. If the first card dealt is a high card, then the probability that the second card dealt will also be a high card is 19/51 < 20/52.
High cards follow high cards or low card follow low cards is ploppy blackjack. Low cards follow high cards is a very crude card counting method. It is NOT a strong enough counting system on which to base playing decisions, e.g., suppose that you have 12 v. the dealer's 4 and the final card dealt to the player to your left is a 10, J, Q or K. You should NOT hit your 12 based on this crude card counting method. Use basic strategy and stand with 12 v. 4.