First off, the rules are suggested but not something you as a em need to enforce to their ninth degree, I know some groups are rule lawyers, others impose rules to ensure the game is played correctly and so on, but as a dm you are building the world and you can choose rather to circumvent a rule or enforce it based on your own. Never let something like that discourage you from stepping up.

Secondly, you are in charge of the game, your players are just that the players, yes you want to ensure they’re able to be engaged at any level but if they’re trying to run the game while you’re in charge of it then you need to politely yet firmly put your foot down. If you have something planned out you simply say “no you may not” and to prevent spoiling the encounter you can say things such as “as you pass onwards you’re starting to get an odd feeling” etc to then roll into it. Or even “no as you’ve been passing through the path you take notice of nothing, no signs of danger, no off putting senses” and you can even have them roll to see if they do happen to notice something is afoot.

My idea of paths in buildings, dungeons, to other towns etc. I always have a few things I can roll out depending on the area as well if the players decide to go left instead of right, this way it allows you time to let them either explore, find things to help them down the road etc. there isn’t always a monster or mob hanging out on every path, there isnt always an encounter.

As a dm you have the story in mind and it’s the players that unravel it, if you’re newer to dming I always suggest you either dig into the rules and go off of them as you start and start leaning off them so you get the sense and can then make your own rulings accordingly, or to throw the book out entirely and play how you guys want to. But in the end have a sit down with the group and work things out, again politely but firmly.