Quote from: RustyNomad on December 03, 2015, 06:05:55 PM

A sending address can be used more than once as it will be used until the balance is zero.

But this will not typically happen when using HD wallets. For example:

Address A has a balance of 1 bitcoin
Address B has a balance of 0.5 bitcoin

If you send 1.2 BTC to address 'X' (the company that you're paying), then it will send 1 BTC from 'A' and 0.5 BTC from 'B". 'X' will receive 1.2 BTC, and the other 0.3 BTC (minus the transaction fee) will be sent to a new 'change' address 'C'. After this transaction:

Address A will have a zero balance.
Address B will have a zero balance.
Address C will have a balance of 0.2999 BTC (approximately, depending on the transaction fee).

Address X (whose private key is owned by the person you're paying) will have a balance of 1.2 BTC.

A future transaction you generate may use address 'C', but it won't use 'A' or 'B' again because they are empty.

Quote from: RustyNomad on December 03, 2015, 06:05:55 PM

If you send funds to that same address again then it will be used again as a 'send' address.

That will be the only way that 'A' or 'B' could be used again. But the only time you would use the same address for receiving bitcoin would be if you used it as a static "donate" address or something like that.