Why don't nimh's need balancing?

[pinkpanda3310]

This is probably a strange question but I've not had much to do with nimh's. When I got into the hobby a few years ago, the very first run I blew the esc and didn't realize until I drove home and unplugged the batteries. So due to being a complete noob I killed two birds with one stone- esc and batteries (nimhs).

Since then I've gone brushless and lipo (barr the tx batteries). I have a few rechargable AA's that get used in various things including a toy for one of my daughters which takes 3 AA's. So I often have an odd number of cells to charge. I picked up a battery tray that takes 10 cells and was going to modify it so the cells were wired in parrallel so it didn't matter how many cells I had to charge. Plus I don't have to worry about how much charge is left in each cell.

All this caused me to think of the above question and what do you think about the parrallel tray idea?