On an eventful final Friday of the season that featured schedule changes at three of the broadcast networks, unscripted fare shined as Fox’s “MasterChef Junior” ended its run on top while ABC’s “Shark Tank” and NBC’s “Dateline” — featuring a new investigation into the Steven Avery case — dominated their hours in demos with week-to-week spikes.

According to preliminary national estimates from Nielsen, “MasterChef Junior” (1.3/5 in 18-49, 4.7 million viewers overall) was down a little from the previous week when a blizzard on the East Coast spiked the Friday-night viewing levels across the board. The cooking competition tied with CBS’ “Undercover Boss” for the 8 o’clock hour’s lead in 18-49 (and appears poised to win outright with an adjustment to a 1.4 in the finals) while dominating among viewers under 35.

“MasterChef Junior” continues to be a strong performer whereever Fox slots the show, averaging a 1.8 rating in 18-49 and over 5.5 million total viewers in Live+7 this season; and among all unscripted series it ranks seventh in 18-49, despite its Friday timeslot. A big favorite among families, “MCJ” is also the most co-viewed broadcast show on Friday nights, contributing to its ranking as the season’s youngest-skewing unscripted series on the Big Four (median age: 48 years).

Following “MasterChef Junior” on Fox, the timeslot debut of drama “Second Chance” averaged a fourth-place 0.7/3 in 18-49 and 2.2 million viewers overall. It had pulled a 1.0 in the demo and 3.75 million total viewers behind “American Idol” in its second and final Wednesday airing last week.

Elsewhere, NBC’s hourlong season finale of “Undateable” averaged a 0.8/3 in 18-49 and 2.7 million viewers overall, placing fourth among the Big Four but matching the show’s top score since mid-October. It was followed by the return of “Grimm” after a six-week break (0.8/3 in 18-49, 3.8 million viewers overall), with the drama matching its most recent delivery in the demo and rising a bit in total viewers.

The Peacock standout of the night was “Dateline” (1.4/5 in 18-49, 4.9 million viewers overall), which hit a season high and matched its highest rating since November 2014; it won its timeslot in 18-49 and 25-54 (1.8/5). The hour featured the story of Avery’s conviction and later exoneration in the 1985 sexual assault case of Penny Beernsteen, who is seen in a rare 2005 interview about the case. The hour also looked at the Avery and Brendan Dassey trials in the 2005 murder of Teresa Halbach, and the latest developments in the drama that has captured national attention of late thanks to the Netflix series “Making of a Murderer.”

At ABC, “Last Man Standing” (1.2/5 in 18-49, 6.8 million viewers overall) dipped below the season-high 1.3 it had been doing for weeks, but again led its timeslot in adults 25-54 (1.8/6) and total viewers, and “Dr. Ken” (1.1/4 in 18-49, 5.1 million viewers overall) was up a tick from its most original. “Shark Tank” (1.7/6 in 18-49, 6.8 million viewers overall), which has slumped some this season, spiked 21% above its most recent original of two weeks ago (1.4) to match its season high and stand as Friday’s No. 1 program in most key demos.

CBS opened with the solid “Undercover Boss” (1.3/5 in 18-49, 7.3 million viewers overall), which was within a tenth of its season high of last week and won its hour in several categories, including total viewers. It was followed by repeats of “Hawaii Five-0” (1.0/4 in 18-49, 6.5 million viewers overall) and “Blue Bloods” (1.0/4 in 18-49, 7.8 million viewers overall), the former of which beat firstrun dramas on both NBC and Fox.

CW had a nice night with the timeslot debuts of former Thursday dramas “The Vampire Diaries” (0.5/2 in 18-49, 1.2 million viewers overall) and “The Originals” (0.4/1 in 18-49, 0.9 million viewers overall). “Vampire” held even with its prior original in 18-49, delivering the network’s best rating in the time period in nearly a year and its best women 18-34 rating (0.5/2) since last March, and “Originals” also was steady in 18-49. Both shows were big gainers in delayed-viewing numbers when they aired on Thursday nights, and figure to see even bigger spikes with their Friday episodes.

In “live plus-3” ratings for Monday, meanwhile, Fox’s “The X-Files” rose to a 4.37 rating in 18-49 and 12.70 million viewers overall, up more than 30% in both from its same-day Nielsen averages; it also picked up roughly 750,000 viewers in 3-day streaming via Hulu and FoxNow, according to Fox. The 4.37 is the second highest for a broadcast drama series premiere this season, topping the “Supergirl” opener on CBS in October (4.13) and behind only the launch of NBC’s “Blindspot” in September (4.45).

Lead-out “Lucifer” grew by 38% in 18-49 (to 3.35 rating) and by 36% in total viewers (to 9.76 million); it also added about 500,000 total viewers in 3-day streaming on Hulu and FoxNow, according to Fox. The 3.35 in 18-49 is the third best L+3 score for a broadcast drama premiere of the past year (since “Empire”) — behind only “Blindspot” and “Supergirl.”

Over at ABC, “The Bachelor” grew 7% week to week in 18-49 (2.90 vs. 2.72) to hit another season high in the demo. And in total viewers, it spiked to 9.13 million — the show’s third straight week-over-week gain since its Jan. 4 premiere.

CW’s “Crazy Ex-Girlfriend” matched its high in 18-49 (0.39) while rising to 1.06 million total viewers.