Remember that those receiving addresses are ALWAYS still good if someone happens to send you coins to one of those addresses again. Electrum will use them once and move to the next one just to help you remain "private". There is no security risk at all to using any address multiple times. Privacy may be impacted if an address gets used repeatedly, but it doesn't mean anyone can get to your coins in any way. That is the logic behind the software!
Thanks! Good explanation!
One reason to use an address repeatedly is during testing and verification of a system.
This may be developmental, or it may just be you - trying out a new piece of software. Like ....
0.001 btc --> address X,wait until it clears.
0.010 btc --> address X, wait until it clears.
1.000 btc ---> address X, wait until it clears.
You get the idea. minimize risk.