really depends on the person cutting. I've had some employees that took pride in what they did and were very accurate and I've had other employees make cuts almost an inch off and splinter the crud out of the board. Just make sure the employee doesn't do all measurements on the board before cutting. This means they're not bothering to account for loss on the cut. The better employees will measure from the blade and mark the panel saw instead of the wood.
That's not sure true.
They can mark the board and know exactly what they're doing.
In most cases, the plywood saws are setup with a 1/16" blade. Some are a 1/8 or a 3/16.
Here is the best way to get it done: mark the wood yourself, and ask them to notch it with the saw on both the rip and the cross cut. For each notch, check to see how it looks.
If they're paying attention, they'll ask you which side of the notch the blade needs to be at.
If they mess up the cut, don't pay for it. If they mess up, they'll call someone over who will notcmess up.
Sometimes, home depot will have s sign that says "we do not perform exact cuts." in their defense, the 3 free cuts you get with a stand at the saw is so that you can get your project home in your toyota corolla. NOT so that they can make you s custom cabinet alternative to Ikea. If they don't want to play ball, that sign they have posted will do exactly what i just typed: they are not your cabinet maker. They are just there to get the product home in your car.
Most folks will be kind and accomodatong as long as you explain yourself well. They've done 1,000 projects "worse" than yours, including an entire 3 sets of Jiant Jenga this week.
Just be kind, patient, and accurate yourself, and if it doesnt work out, go to Lowe's.