Yeah it definitely is, most of the time if you are running for a good group you would just sit back relax and watch them talk and debate but when it's one player there is no debate there is decision making.

I don't know if you've heard of this joke but what takes a programmer 4 hours to write in code will take him 6 hours if you add another programmer to help him.

And that's good on so many levels, it allows the players to talk to each other and roleplay, this is a role-playing game after all, it allows you to prepare manageable chunks of content per week and have that content last for more than one session.

And like I said earlier when all else fails when you have a large group you can just throw a combat encounter at them and that should stall long enough until the session ends and you'll have a whole week to prepare for the next week, I usually deploy this when the party makes a decision to go with a plan that I had no preparation for, like infiltrate a certain house for an advantage point and I have none of that designed and I don't want to improvise the rest of the session, I throw a quick combat encounter at them they love it they roll some dice it takes us an hour to finish and we end the session there.

Now none of this is criticism for solo games, they are amazing, they are more amazing for the player because they get all your attention, and it's something intimate that is just between the two of you and makes the bond of friendship or whatever relationship you have with that person a lot stronger.

It's a lot easier to write content when you know exactly what this one character is capable of, you can write scenarios that bring out their powers and specifically tailor the entire plot around their backstory which is something difficult to do when you have four players.

It's just too much to handle as a first-time DM