Linedef Type 52 - Continuously Falling Sector desperately needs more variables. Here's what I propose:
Front-side texture x-offsets: Time delay in tics to wait after level load before the linedef starts working.
Front-side texture y-offsets: Time delay in tics between when the falling block disappears at the bottom and reappears at the top.
I'm actually astounded that this hasn't already been done. It's logical, and it would help tremendously with customizing the falling blocks. First of all, it would allow the top and bottom of the block's path to be much shorter, using the time delay in place of a ridiculously high/low control sector setup.
Second of all, and even more important, it would allow different falling blocks of the same speed, high point, and low point to be unsynchronized. You can't tell me that this wouldn't have made your lives easier when you were creating the waterfall gimmick in DSZ2, and it might have made the gimmick function better, too. There are some parts of Tortured Planet that would benefit from having this option as well.