The transaction log for the database fills up overnight everyday
I think your problem could actually be that you only want to backup and shrink your transaction log once per day.
If you don't need Transaction Log Backups to restore to any point in time, then switch your recovery model to &quot;Simple&quot; and stop doing log backups altogether.
If you do need Transaction Log Backups, then you usually have a need to take more than 1 in a day. SQL Server will track every change in the Transaction Log until the Transaction Log is backed up, so maybe try scheduling these to run more often.
Before you backup and shrink the file, or whatever you're doing each day, you can run the following command to tell you what it's waiting for:
SELECT name, log_reuse_wait, log_reuse_wait_desc FROM sys.databases;
Given that backing up the transaction log fixes your problem, that's where I'd put my money. But other things that can cause the Transaction Log to continue to grow are Mirroring/AlwaysOn replicas falling behind, long running transactions (which will affect Simple recovery model as well). The above query will help you find the problem.
Finally, having a large transaction log is not actually a problem. You shouldn't shrink the file every night, it's just going to grow again tomorrow. If log_reuse_wait = 0 then just let it be. If log_reuse_wait is not 0 then check before you clear the log what it's waiting on. Microsoft Docs has the full list of codes.