I run the registered Pro Version of Avast along with the Pro Malwarebytes and recently ran a complete scan with both and found nothing. When I ran a bootscan, Avast found 42 Rootkits and Trojans and deleted them. I'm a believer in at least Monthly boot scans.
I'm a little puzzled??? Once a boot scan has been run, avast! has checked all the files that are possible to be checked.
Thereafter, anything added or changed is automatically checked.
Why run a boot scan weekly
Does it make you feel better
Your computer, your choice.
I for one have better things to do than wait for scans to complete.