Aachen (where my brother studies) - 3 days
Brussels - 2 days
Bruges - 2 days

OP can count - if I look at the beginning of the trip, travel is inexistant.
Aachen - Brussels is about 1h30 ? Sleep close to Aachen, and arrive in center of Bxl : 2 hours max.
Bxl - Brugge : 1h30 of train : same

Not everybody needs 2 hours for breakfast and checking out.
And breakfast can be eaten in the train.

So I find the travel well balanced for young backpackers.

Ah, forgot : LOL, MDR, LOL, ROFLOL etc.

Ooops, my mistake, subtract one night from Prague, one extra mystery day.