I personally think it would make the gameplay more fun if you have all the options available since the beginning even if it means that in certain paths, the game ends early. The whole point of a sandbox game is that it gives you more freedom on how the story progresses and which characters you want to focus on first. If you need more than one playthrough to unlock all the paths anyway, then why would anyone bother with playing the sandbox mode? It's way easier to just replay the VN mode make different choices, skip all the text that you've already read and avoid all the grind. A lot of people already hate the idea of having to grind in adult games, having locked paths makes it even worse. But this is just my opinion and I know it's not worth much.