Too Large Tubes . . .
 

I am mounting some 26 x 1.50" tires and all I have are tubes for 26 x 1.95-2.50" tires. Will these too large tubes work?. Can I get away with being super lazy?

You'll be fine. I have a bike with 700x35 tires and 700x19 tubes. You really only need to get close with tubes.

Yep, give it a try. If it doesn't work, you'll know right away.

You can predict in advance how they'll fit. The unstretched diameter of a tube is 1-1/2 times it's flat width. So measure, multiply, compare and decide. Don't forget that the tire has some thickness, so it's inside diameter will be slightly smaller than the stated width.

If the numbers are close give it a go, but if it's obviously too big, save yourself the wasted effort.

I've used 1.75"-2" tubes on 1.5" tires many times, no problems. If the tube is too big it will have a crease that over time (long time) might rub and wear out causing a flat.