I'm old enough to remember KOOL-TV 10, so I remember when KTVK's news was a joke. 10 and 12 were dominant.
Then 3 got tired of losing and hired 10's brain trust. "Newschannel 3" owned news in Phoenix for a long time and even if they didn't win outright when all the affiliations swapped they were strong.
When 3 lost its ABC affiliation, news was the still best thing on KTVK's schedule (and making them a s--tload of money), which is why they added additional newscasts when they became independent.
15 had no news department until maybe the last year they were Fox. They launched a quick paced "no chitchat more news" format that I personally liked but went against all TV news norms and they aggressively hired some of the best in the valley to staff their newsroom to get it launched. When Fox bought 10 and Scripps made its deal for ABC, they moved more towards a traditional newscast. But since they had hired experienced photogs and desk people, even if most of the on air talent was new they knew what they were doing.
KNXV actually intended to launch a 9pm newscast in the summer of '94, along the lines of what KSHB Kansas City had started the previous year — it would have been pretty Fox-y. They were already building their operation, picked up a set, and hired an ND by the time ABC came calling.
In order to meet the demands of their affiliation change, they kept the format and the set, but hired nearly triple the expected staff, and moved their 9pm news to 10pm (and delayed its launch to August 1). Not long after launching, they had a change in ND, as they had hired someone with a 9pm news in mind.