If you were expecting Persona 5 Royal to be even longer than Persona 5 -- which is already an incredibly lengthy game sitting at around 80 to 100 hours -- then you may be happy (or unhappy) to know that Atlus has spoken out on the subject. According to the developer, Persona 5 Royal will be about as long as the original, despite the fact that it incorporates a load of new stuff like additional social scenes and expanded gameplay mechanics.
So how can it be the same length as Persona 5 (or, as Atlus estimates, "slightly" longer)? Well, the team says it's down to optimisation. Apparently, load times and the time it takes to complete battles have been shortened, while palaces have been "optimised". We're not entirely sure how this works out -- as far as we can remember, Persona 5 doesn't have very long loading times to begin with -- but again, this is what Atlus says.
Basically, it sounds like Royal's been streamlined in a number of ways, and this makes room for all the new bits and pieces. The game's out in Japan in just a few days, so we'll no doubt learn more once people get their hands on it.