Make LB length 60 seconds by default & make internal source have evolving LB

Those are very small changes but tell me if you prefer them in two different commits.

For an unknowm reason I was not able to assign this merge request to anyone. It was meant for @rhauser

Reassigned to @rhauser

Status changed to merged

Mentioned in commit 98924f9b

I got the notification last week, but then was some urgent bug discovered by our L1CTP colleagues, so I did that first. I've merged the changes into master