This is something what is being configured by Microsoft script best practice configuration.
To be honest, I wouldn't trust some of MS's recommendations. You cannot make a blanket statement as to how big TempDB should be. I've had servers where TempDB was over 200GB. In fact, I can't recall a server that I've worked on in the last 5 years that got a 50MB TempDB, even my desktop has it set at a couple hundred MB. The size of TempDB is defined by the workload on the server, not some statement in some old best practices guide.
Also, we do 15 min tran log backup, and full database backup.
TempDB can't be backed up, and backup frequency of user databases won't have any effect on TempDB size
Microsoft Certified Master: SQL Server, MVP, M.Sc (Comp Sci)SQL In The Wild
: Discussions on DB performance with occasional diversions into recoverability
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