Another veneer question

I've successfully applied the veneer to the table tops of my project. After some reading, is it really necessary to apply the veneer to the back side of the substraight as well?
I'm using 1/2" birch ply as a substraight. I would have thought that this material is pretty stable, and does not need a veneer backing to prevent moisture absorbtion or wood movement.
What do you think?

how are you using the panel? if the cupping is restrained physically some way then i don`t do both sides.....but if your design allows for the panel to have the ability to cup then you should do the other side to combat the cupping.

conventional wisdom

An uneven number of plys makes for a 'balanced' panel. Too often we think only of the immediate use and environment of the piece we are building, with no thought that someone may consider it a 'heirloom' and be in despair down the road when the piece fails because we didn't think ahead. To hold down the cost, use a 'backer' ply. That's what they are for.

Remember that the builder doesn't get to determine what is an heirloom and what is not. Just do your best and use the best methods.

From the perspective of a former woodworking instructor and one who has moved around the country quite a bit the last few years. Different places. Different ambient temperatures and humidities. Wood behaves very differently from one place to another.

Thanks for the replies. The cupping may be avoided because the veneered panel has a 3/4" X 2-1/2" boarder around all four sides. And as for moisture, I'm going to seal the under side in the finish process.
I didn't now there was a 'backer ply', I didn't see that product in my local wood working store.

A backer ply is a veneer of the same or very similar density and thickness as the show veneer. Let's say you're doing something that calls for a walnut burl, which is one of the more expensive veneers out there. I would think you might use plain walnut as the backer veneer.