Both. If you look off the roof of the Contemp, you can see a bunch of patches that have been done because pieces of the beam will fall off. It's not just there, but its easiest to see there. And the patches can't be made until after shut down. Say the park closes at 11, the beam will probably finally be shutdown at around 1:45am. Then the work tractor will need to make its way to the section of beam that needs patching. They will work on that, and by 5:15 the openers are showing up and that tractor has to be done and back at Shop by 6am at the latest. That only leaves about 4 hours for the work to be done AND for the concrete to dry. If it's not dry enough, the patch falls off a few hours later, the trains are reduced to "walking speed from Pylon x to Pylon y then resume normal speed" and the process repeats itself. If the park is open until 3am, the Resort beam stays hot throughout the night. The only maintenance the trains on Resort beam get that day is a quick check with a flashlight under the wheel-well covers (which are having a tendency lately to come loose and rip off trains as they enter a station) and they scan the AMVS and say "10-8, good to go." Generally, those Resort trains that never got a chance to go back to Shop don't make it through the next day without an unexpected trip back, with the ensuing downtime.
Also parts are literally falling off of the trains. Green's collector shoe ripped up a piece of buss bar on the 3rd of July which caused not only the train to go down but also the beam. Green also I believe was the train that caused a transmitter to fall off the beam between MK and GF and start a grass fire.
I have had a bus driver come up to me with a piece of a train that fell off into the bus loop and say "I think this is your guys." That's not embarrassing at all......
A few weeks ago I watched a Monorail shower down sparks on a group of Guests just as it enter MK on Express. That train went immediately to shop, but to add more drama to the scene, Security went running underneath the train all the way to the Switchbeam yelling "STOP STOP!" to any Guest who attempted to, heaven forbid, WALK underneath the Monorail as it was moving. That scene, to me, was the straw that broke the camel's back for my pride in that department.