I could not figure out why not use the with:
Are you working (the) next week?
We’re going to plant some new flowers (in the) next spring.
Ollie’s coming to stay the week after (the) next.
You are (the) next.
Though it has been used in:
I don’t know how I’m going to manage from one day to the next.
I’ll finish the work in the next few days. You can pay me then.
The next person she met was an old lady who had lived in the village all her life.
Please explain the rule.