I do not feel comfortable with Smart Scan Completing in 5 minutes or so, when other scans, like Malwarebytes, for example take 30 minutes or so to complete. It just seems that it is not doing a thorough enough job !
The problem being you aren’t comparing like for like as you can’t directly compare what is being scanned.
The avast Smart Scan is by its nature highly optimised (Smart you could say).
On demand scans are somewhat depreciated in resident on-access AV, files that are active are going to be scanned by the on-access scanners. For the most part the on demand scan is going to be scanning inert or dormant files, which would otherwise be scanned by the on-access scanner if they were active.