Faizal made a great point here.

Practicing the 5 minute test does not mean right away, your 5 min test will improve. If you see the 400 meters runner's athlete training, the core of it is 200 meter sprint...They almost never run the 400 in trainings, except when they are close to the competition.

And we have many examples in the RKC community, when people did press the 48 kg, even though they biggest size KB was 32 kg what they practiced with.