#5 WWE frequently changes the official entrance intervals
Traditionally, most Royal Rumble matches have featured intervals of two minutes between competitors' entrances into the match (officially, of course; the times mentioned in this section are purely kayfabe, as WWE will frequently stretch its own timing rules during the match in order to structure the contest better for the live crowd and for the television broadcast)
The 1995 edition of the match shortened this interval to 60 seconds, partially to quicken the match (its biggest critic was always Vince McMahon, who felt the contest often dragged and was too long) and partially because the contest's winner, Shawn Michaels, was a heel who would be entering from the number one spot. WWF creative feared that HBK winning while also being the contest's longest-lasting competitor in history would force a babyface turn (an idea Bruce Prichard has said McMahon was vehemently opposed to at the time), so the intervals were shortened.
New Champs in WWE! More RIGHT HERE
The intervals changed again in 1997, as the then-most-attended Royal Rumble match saw intervals of 90 seconds between competitors; WWE has alternated between the 90-second and the two-minute intervals for the past two decades, with 90 seconds being the norm throughout the rest of the 90s.
WWE's 2018 contests, owing both to momentum and to the fact that the broadcast would feature two Royal Rumble matches, kept the intervals to 90 seconds