Pattern locks have one advantage
Smartphone “pattern” style lock screen suck. They’re innovative, but ultimately an inferior variant of the numeric PIN lock screen in almost every way.
The pattern lock is essentially just a numeric PIN where the numbers must form a continuous line. Each digit must be adjacent to the previous digit, double digits are impossible, and there is no zero. This considerably limits the number of permutations.
For example, on a 4-digit line, only 952 of 10,000 possible numeric PINs form valid pattern locks, and for 6-digits only 22,272 of 1 million possible PINs are valid pattern locks.
Furthermore, there are general human biases that make it more predictable. People probably start near the top left, and incorporate a lot of movement or use simple patterns like letters. For example, a Z-pattern or spiral are probably more common than the equally valid “898969”.
Worse, the smudge left on the screen by a swipe is greater than that left by a tap, and provides greater information about the order in which the digits were hit.
All this said, pattern locks have one advantage over numeric PIN: you can’t enter four of the same number. It’s impossible to enter a code like 1111 or 0000, which are usually the first guessed.
This isn’t enough to make it a secure choice, but it does at least protect users from making the most common PIN mistake.