This subject is present everywhere and on a daily basis. However, that one sector is the bad part of the whole issue.
Let's assume that this fire loop problem has been addressed to, a rectification has been attempted and mentioned in the techlog accordingly. Now, crew flies from A to B and they know about the issue and they do not want to enter the problem in the log again on the outbound leg as it will a have to be actioned upon with a deferral at least.
How many calls do you guys expect to reach crew at this stage and ask them to "bring it home and we look here into it."
Now, if you bring it home, first sector was without any problem, at least according to records, and a new DD can be raised.
This happens often enough and problems will be carried around for a prolonged period, mostly until the next hangar visit during the next check.
I am not implying at all here that airplanes fly around with problems, nor is it my intention to picture the idea that airtravel is unsafe due to companies "interpreting" the law their way but, especially during this time of the year and the ridiculous EU-laws about compensating passengers for delays etc. the pressure can be high on everyone.
A change of wording to "the following two sectors remain faultless" may save a lot of heated debates...