If all of your journal entries were posted properly (and error-free) in the general ledger, your debit grand total and credit grand total should balance, and you can move on in the accounting cycle. If the debit and credit grand totals do not balance, then you have an error to find somewhere in your transaction posting process (journal to general ledger to trial balance).
It's possible to have a posting error even if the debits and credits do balance, but that will get found and solved later in the accounting cycle. Examples of problems that would not show up in the trial balance include:
- Putting the credit amount in the debit column and the debit amount in the credit column for a particular transaction;
- Recording a transaction in an incorrect account;
- Forgetting to record a journal entry as a general ledger transaction;
- Neglecting to make a journal entry at all.
Preparing a trial balance more frequently means that you have fewer transactions to go through, so if there is an error you can (usually) find it more easily. Once you have a balanced trial balance, you can proceed to adjusting entries, the next step in the accounting cycle. Remember, though, you don't have to wait until the end of the accounting period to prepare a trial balance!