That's pretty poor (but par for the course). Anyone checking early morning before setting off a little later would get no warning of a problem that TfL could have told them about.
On the other hand, on my several Underground journeys in the last few weeks, I've each time been assailed by frequent announcements (irrespective of what line I've been on) that the District is "part suspended" between Earls Court and Olympia. For a minor and infreaquent service (with a diversion available, as well as a bus alternative if required) which doesn't even run every day (I believe that's still the case?), I've been surprised to keep hearing it.
But I echo the question - why so long anyway?
More or less on this topic - ie constraints on platform usage at Earls Court - I understand the explanation earlier in this thread about the line from High St Ken coming up on the south side at Earls Court, hence only being able to access the one westbound platform there, means that the points which are currently out of order stop those services from afterwards proceeding west rather than south. But as far as I can see, there's also a constraint - which there doesn't so self-evidently need to be - for trains coming from the south into the eastbound platforms at Earls Court.
These arrivals can only access platform 2. Yet most of them are destined to "turn left" after Earls Court, and hence there would be fewer conflicting movements east of the station if they could arrive on platform 1. Assuming that most trains from the west will arrive onto platform 1 [though they could come in on 2], to balance the platform loadings with the services from the south being confined to 2, and given, also, that after leaving 2 you can switch to the line out of 1 immediately, but the opposite move (to head east rather than north from 1) is only possible at the last moment before the north-most track turns north, then surely this means that the stretch of track due east of 1 must carry the vast majority of trains leaving Earls Court eastbound, with the stretch of track due east of 2 carrying quite a small proportion.
To my amateur logic, this seems an unnecessary restriction on flexibility at Earls Court. Is it not possible for trains from the south to be allowed the option of arriving into 1, and/or for there to be a switch possible "from 1 to 2" immediately after the station, as well as vice versa?