Not as much lately, but for years, WWE would go through announcers like a hot knife through butter. With how much they value a "TV look," they've tried out a lot of announcers that, for whatever reason, didn't work out in the long term. A number of low-level announcers came and went, lasting anywhere from a few weeks to several months. One example I didn't include in this list, since he made it on to a pay-per-view event (SummerSlam '93), was prolific infomercial host Joe Fowler.
Maybe it was longer, but it felt like he was gone within weeks, back to selling me wonderful doodads I can't get in stores. They also experimented with a number of existing wrestlers and managers as color commentators, interviewers, hosts of the "Event Center" segments, and so on. Just think of some of the higher profile experiments over the years: Shane McMahon as the original co-host of Sunday Night Heat, the Honky Tonk Man on Superstars of Wrestling, Lita on Sunday Night Heat, older wrestlers like Tony Garea and Angelo Mosca early in the expansion era, Tammy "Sunny" Sytch as Tamara Murphy in the Event Center, and so on. You get the idea: There used to be tons of turnover.
Let's look at some of the most obscure of WWE's announcer runs.