Yes my contracts will change as I take on new clients and add in more paid days, increase fees and add additional policies. They are basically the same for all, but I do fine tune with each new family, so rates/policies may vary slightly.
Your late fees aren't high enough to discourage it. Mine are $20 for each 1/2 hr, but it starts at 1 minute late, so it's $20 at 1 minute after closing. That's why they need backup people for pickup.
Only had this happen twice in 5 yrs, so I guess it works!