Checkpoints
aid in limiting or negeting cuts, as do models and terrain, but sometimes even that isn't enough lol. On Alpine's Crazy there's a huge cut in it that all but ruins the track in my opinion. It involves doing a quick H-H stop off a ledge, which allows you to drop down to a lower level of the track, trip the cp, and proceed on. I think it knocks off about 11 secs lol. Then there are tracks like Reospeed's Adventure into Nothing (lol just discovered that one's not at MTMG, but I'll fix that on my lunch break) or Monte Carlo whereby the linear layout all but make checkpoints useless.
Seriously speaking, you would be amazed at some of the shortcuts that people come up with. If I have time tomorrow, I'll make you a replay of the cut I came up with on Banff Springs lol. It's kinda freaky, and you would never think it could be done, but I'm telling you, there have been some pretty innovative shortcuts thought up over the years.
For instance, on ZS Rally, after tripping the last cp before the finish, you can call the heli and it'll zip you back to the finish line lol. The heli doesn't work in that track anyway; it takes you back to the start/finish by default and most everyone knows that, but after tripping the 2nd to the last cp, that's where you wanna go anyway.
That's not due to faulty cp placement, sub-par terrain work or insufficient model placement; it's just an example of what some of thes guys come up with out here.
In the end, like everyone else has stated, it depends on the track and how the author uses the terrain, models...and water. One thing's for sure, it would be weird running a track with only a start and finish line for cp's lol. Everyone's so accustomed to having them. Still, if they're not really needed, I say leave them out.