My son (currently 8 months old) is quite content to sit by himself and play with toys (blocks, toy cars, etc.).
We make sure that he spends time interacting with other children, and we also make sure that we spend one-on-one (and two-on-one) time playing with him, reading to him, singing, etc., and he clearly enjoys those activities. However, he seems equally content to be on his own.
My assumption has been that play time without interacting with other people would help him develop some independence, and hopefully help teach him not to be bored when no one is actively entertaining him. However, I don't really have any research, or even experience, to back this assumption up.
Is there benefit to him spending time playing solo? Is there a certain amount of time he should spend playing by himself each day (or a limit to how much time he spends playing by himself)? Does this change according to developmental stages?