#1. Don't overexpose the Fiend
In WWE, most of the Superstars have to work for around 300 days a year. Most of the Superstars have to work RAW and/or SmackDown LIVE followed by the heavy schedule of house shows. Since WWE has diluted the brand split rules, some of the Superstars are regularly appearing on both Raw and SmackDown LIVE, and thus getting overexposed during the process.
Take WWE's top full-time Superstar, Roman Reigns, for example. The Big Dog is wrestling on almost every episode of both RAW and SmackDown LIVE. Even though that may look good, the sad fact is that such a work schedule is overexposing Reigns. His fights don't feel much special anymore due to that. On the other hand, the fights involving Brock Lesnar, who fights only on select PPVs, feel much more special.
WWE should not make this mistake with The Fiend. The Fiend should be used very sporadically. He should not be summoned for the sake of filling the match cards. Sure, WWE could use The Fiend to interrupt segments as he did with Kurt Angle or Mick Foley. But they should not waste an entrance from the Fiend on regular TV shows.