Sometimes, with LCC it can be cheaper, but more time consuming and complex, to travel through the main hub eg
I flew BKK-KUL-PEN on AK (Air Asia) as it was cheaper than BKK-PEN on FD(Thai Air Asia.
BKK-REP can be accomplished via 3K/JQ routing BKK-SIN-REP, or AK via BKK-KUL-REP.