Let's imagine it's currently Wednesday the 1st. Does "next Saturday" mean Saturday the 4th (the next Saturday to occur) or Saturday the 11th (the Saturday of next week)?
Absolutely this. Because it is never clear which is meant without being qualified, you have to do this every time unless you specify. I would just say Saturday the 4th to save the exchange.
Thinking about it. Couldn't it be argued that its actually quite efficient?
You have lots of words that have multiple meanings and the difference is i the context, the tone, and the words used in conjunction with them. For example.
Fuck.
It can be an insult, a proposition, an exclaimation of pain, a state of repair etc. And all these things and the rest can be expressed with that one word.