One can do this 80%/20% split. Not sure if it's mentioned in some official guide or it developed through trial and error. Usually the 20% is reserved for bug f

One can do this 80%/20% split. Not sure if it's mentioned in some official guide or it developed through trial and error. Usually the 20% is reserved for bug fixing tasks which can't be estimated and therefore can't be included in the Scrum framework. One of my projects has a "technical backlog" which is actually just a Jira task with multiple subtasks which gets dragged from sprint to sprint. As you can imagine this doesn't work so great from a process/tool perspective, but it gets the job done (i.e. Major refactorings can be and have been performed). The thing with Scrum is that a lot depends on the PO and SM. If they're open minded and experienced you can get something decent. If they're dogmatic and pray at the altar of Jira, prepare for suffering.