Both of my centers are 24 hours. Now I do not own them, simply manage so I am not familiar with the insurance part. However what we do at Snap Fitness in Bismarck (this is not nationwide just our locations) is staff them Monday – Thursday 11-7 and Fridays 11-3.The doors remain unlocked during those times, otherwise key cards must be used to enter. My trainers come and go from 5 am until 9 pm. All of our trainers are either Snap employees or independent contractors. We have surveillance cameras in which we can monitor from home or at the club going back within certain dates. We also have lanyards with a direct link to our security system and emergency buttons. When you state leave the doors always open you would want them locked at the point it is not staffed with a way for members to access them.
I am unsure what you mean by keep their credentials in regards to your question. We have had an issue with trainers not hired by us coming in when we are not staffed and training others – however it is usually caught in some way and addressed.
Just keep in mind – the more you are staffed the more success you will have. Whether it is with new members or PT revenue. Just because the gym is open 24 hours does not mean it will be more successful. It may mean more overhead cost. Difference in insurance. It may be the opposite you may open up to a whole new market if you don’t have many 24 hour near your area.