Is it worth running a Boot Time Scan when Windows 11 has Secure Boot?
Why are you thinking to run a Boot Time Scan?
For me, this would only be used when your PC is misbehaving and Full Virus Scan has revealed no malware.
IMO, No on-demand scans are needed these days, as the real-time protection should keep you safe and clean.
Personally I would say not without the correct circumstances/criteria.
e.g. If you have encountered a virus/malware on your system that Avast can’t deal with when Windows is running.
That would be a rarity.