Unfortunately, Pit's speed when zipping is the same as his normal speed, so I don't think it can be used in this sense.
But on to some good news: here's a movie showing that it might be possible to zip from left to right, at least under certain conditions. In this movie I fall into the layer below me and jump my way out of the wall, getting pushed from left to right. I don't know if this can be put to use, but it's a cool trick none the less:
http://dehacked.2y.net/microstorage.php/info/1552998004/kid_icarus_fall_zip.fm2
In any case, it would seem that we have not yet fully discovered everything about this wall zip trick.
Also, if you're interested, here's some more info on zipping through walls:
As you know, each block is 16*16 pixels. Blocks don't have collision detection for Pit's feet for the top 7 pixels, so while his feet are still in the top 7 pixels, he can move around freely inside the block.
So what you want to do is make a jump that is just short of landing on the block, thus giving you the highest possible y position before starting to fall through the block, making the most out of these 7 pixels. If done correctly, during the time it takes you to fall these 7 pixels you will have moved far enough through the block to reach its left side, making it push you out on the other side.
After some practice, this wall zip is quite easy to pull off with TAS tools. You have great control over jump height, since you can tap the A button during jumps to fine tune the jump height. You can try this yourself, monitor RAM address 001D when jumping.
This just saves you the time it takes to walk through the room, so it's about 1-2 seconds, but still something