Do what You're Going to do.
Time it. If it's too long cut down on any long-winded dialog, elimate any unneceasry characters in their way, turn up some of the lights in the darkest parts, make the path more obvious with doors held open, especially if they are things that have to be found by the customers.
If it's too quick do all of the former ideas in reverse, add dialog, add characters , obscure the path somewhat...
You have alot of power to adjust it and make it more what you feel that you have to have.
Unpredictable scares can have whole groups running but running is hazardous in my opinion and should not be called for or overly inspired or allowed to be a normal occurrence.
Yes, many younger people can run and have no problems but that is not how it is for all of the people coming through any haunt.