An 'emerge -pe world | genlop -pt' today gave as answer: Estimated update time: 1 day, less than a minute. Attached patch fixes this.
Created attachment 78148 [details, diff] don't print 'seconds' after days
genlop has been moved into gentoo's svn per permission from the original authors to take over maintainership. The fix for this bug has been added to svn, thanks!