Comment by lxgr

Smaller spot beams are still technically possible for an Iridium-like constellation with fewer satellites. That's what e.g. ASTS is doing.

In fact, more than one (or maybe two, for geometric reasons near the equator where polar orbits are sparse etc.) satellite concurrently visible is pointless if the ground station/mobile device isn't also heavily directional, which is not the case for small, quickly moving handheld devices at least.

One other reason for wanting more satellites splitting footprint coverage between them would be if the satellite transmitters were transmit power limited.