Luke 1:8-9 "Once when Zechariah's division was on duty as he was serving as priest before God, he was chosen by lot, according to the custom of the priesthood, to go into the temple of the Lord and burn incense."
"...by lot..."
"...according to the custom..."
There may be many things in life that appear to happen by chance, or seem to be routine and regulatory. Nevertheless, God governs over the affairs of men.