I do not know your understanding of transactions. This is not meant to be insulting, just hopefully informative.
I am not an expert, but based on my study of transactions, it depends on what the wallet generated for the transaction. Only enough transactions should be included to cover the amount being transferred out. Whatever generated the transaction appears might have included all unspent transactions in the wallet for the source funds. It does not list what the amount in each transaction was at the time, so this is laborious to determine based on the info provided. It does not show what happened to the bit-change. I appears it went back into the source account.
Even if you have/use only one account number, a transaction is defined by previous transactions for the source funds. This can make for a long list depending on how the transactions are selected. Transactions are not pooled like a bank (except having the same account number); they remain separate. If multiple account numbers are involved, the transaction gets longer. The shotgun approach would be to throw everything at the transaction and let the change/excess go to the change account. This would be a very poor approach.
See:
https://en.bitcoin.it/wiki/Transaction
