With a more powerful router you could do it in one pass with a 1/2" bit.
Having a router that will except 1/4 and 1/2 inch shank bits opens up a lot more cutters options. That can be a big plus.
Cutting thru 1.5 inches of wood with a 1/2" diameter by 2" long bit goes pretty smooth. That tool will be pretty darn rigid even at 2" long and won't chatter as long as you don't bury it. Stepping over with a small diameter tool leaves more room for error with uneven depths of cut and is also much more time consuming. My Bosch router has a plunge and a solid base. For me, not having the plunge base would have been a real bummer even with center cutting tools.
Also consider if you want to make a good size chamfer or radius those tools are going to be large in diameter and will usually only be available with a 1/2 inch shank.
A 3/8 diameter router bit with a 1/4 shank is on the left. The rest are 1/2 inch shank bits.

I don't usually express my feelings about one product or another as there's always someone that will put it down. But in this case I would like to say that the West System Epoxy is an invaluable tool in anyone's tool box. Not affiliated.
Steve