For 5 (maybe 6) and 3 ngones, you can often just apply a subdivision level to your 3D poly model before saving; you will get a full quad model.
It also works with any type of ngones, but the topo result might look unpleasant.

Chasing ngones is a good thing, but at the end, it's the number of edges connecting to a single points that will create "ugly" result (bad topology flow), and it's often way more tedious to fix.
If it's just to satisfy some loader restriction, pre-subdividing the mesh can be enough.