One GEO is enough as it can be accessed from half of the planet. I don’t want to send a constellation of satellites into LEO. Redundancy can be achieved within the same satellite.Ofc, not one LEO or GEO is enough and not only because of the regional coverage or lack of it - it's about redundancy and resilience.
But, why GEO? And, what is the purpose? It's okay for Inmarsat, but nothing else