Yes to the bolded.
Which is usually like 2 to 4 skills per combat, which, with the defautl skills of a demon, is absolutely doable with the RNG fusions. The rest is having a balanced party to handle different situations. What you're describing is having a jack of all trades, who excels at everything.
SMT IV and P4G were such failures on the challenge point exactly because of this point: you could have one persona/demon with no weakness having access to the most powerfull magical spells, and one for the physical skills.
The goal of the press turn was to have you get a balanced party, with a variety of personas/demons covering different situations, not a couple one that could handle everything.
Planning all 8 skills is the "lazy" way through which you want to steamroll everything without having to change personas/demons. That, and the understandable wish to have OP demons/personas.
But from a balance point of view, you absolutely don't need to have free skill choice.