Time compression does matter but the reality is that they locked into "the conveyor system" after Savage and never got out of it. This is a mindset that has damaged a lot of careers and let to these large numbers of reigns. If you don't win the World within 2 years of your first IC, you are generally a failure and not "main event". It's led to a lot of guys getting World titles who had no business ever having one at all and a lot of talent who could have being overlooked. There was no reason for Matt Hardy not to get a WWE title reign other than others were ahead on the conveyor belt, they couldn't pick every single one so some get missed... Barrett is likely to suffer the same fate.
Time compression works in reverse also for the time for a guy to win that first title... its still as above but now if someone isn't main eventing within 2 years OF BEING ON THE ROSTER AT ALL. They are failing... Bret was on the roster for 8 years before he won the World title, Shawn was there for 7... Mark Henry was on the roster for nearly 15 years before he got the title! How many guys would EVER get that kind of chance? None, never again (unless they gave Dustin a brief reign as a reward) cos they can't invest that kind of time... they can't invest 3 years now...cos there's a conveyor belt of new faces to try from NXT...
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The business in terms of storyline development moves way faster now than it did years ago due to the monthly production of PPV events and need to fill main event caliber matches on live TV every Monday. In 1987 for instance Flair was champ almost all year except a two month window from late Sept to late Nov. He took no significant time off, wrestled in the neighborhood of 250 matches, yet how many actual feuds did he have ? Nikita Kolloff was a carryover from 1986 (Oct 86-Feb 87), Barry Whyndham (late Jan 87-April 87), Jimmy Garvin (May 87-July 87) and Ron Garvin (Aug 87-Dec 87). There were occasional matches against the likes of Dusty Rhodes and Ricky Morton, older feuds from previous years, but he essentially was the No. 1 guy for an entire year and had only 4 opponents, one of them a hold over from the previous year. Today the champ can have 4 opponents in just 6 months, maybe 7 depending on time of year (stories move faster in non peak times away from mega events like S-Slam, S-Series, etc). With that titles are going to change hands faster because the stories are progressing faster. How many fans were upset after the 2nd Cena-Wyatt PPV encounter saying they wrestled twice, Cena won, move on ?
The old WWE was very similar, with a "Title by attrition" approach rewarding those who had been good soldiers and popular with runs whenever Hogan wanted time off. Again, things moved slower back then so they got longer runs during Hogan's sabbaticals. Its just the evolution of the business from a media presentation side. The reason Hart waited so long for a title run was when Hogan was taking time off in 1988 & 1990 he was a tag team wrestler and not a viable singles star, unlike Savage or Warrior (
or Slaughter for that matter). Hart kind of lucked into the title when Warrior injured Flair and got fired, right after Savage took himself off the road. He proved his worth moving forward however. HBK wasn't even as big as Hart for most of his time in WWE, a mid card tag team at best (compared to The Hart Foundation, alongside The Road Warriors, British Bulldogs, Midnight Express, and Rock & Roll Express as the most popular teams of the era) and his singles run started 2-3 years after Hart's did. He simply wasn't ready. However Yokozuna & Kevin Nash got title runs very early in there careers in WWE back at that time, as did Steve Austin
(though Austin had been a major star for a decade, he was in his Stone Cold act in WWE only 2 years before winning the title). Therefore the idea of giving new guys the ball and letting them run isn't something new in WWE.
As for NXT, they don't get nearly as much talent from there as they were getting in the 80s and 90s from WCW, AWA, ECW, World Class, & UWF. WWE & Vince McMahon routinely pillaged other established company's talent on a regular basis in the 80s & 90s for a constant turnover in their roster. Starting from the early 80s and into the mid 90s just look at WWE's stable of stars ...Roddy Piper (NWA), Hogan (AWA), Flair (NWA), Ultimate Warror (UWF), Savage (Mid South area, worked for his father's promotion), Ted DiBiase (Mid South), Rick Rude (NWA & World Class), Jake Roberts (part of Paul Ellering's stable in the NWA), Road Warriors (AWA & NWA), Kevin Nash (WCW), HBK (AWA), Scott Hall (AWA & WCW), HHH (WCW), Undertaker (WCW), Sid Justice (Mid South & WCW), Jerry Lawler (Mid South), Jeff Jarrett (Mid South), Steve Williams (Mid South/UWF/NWA), Austin (Mid South & WCW), Mike Rotunda (Florida/NWA), Boss Man (NWA), the list goes on. NXT doesn't contribute near as much to roster turnover or the desire to move guys quicker into title contention as the McMahon's pillaging of rival promotions used to.