You do not need to learn how to analyze algorithmic complexity from a theoretical point of view, which would be very math-heavy.
But a college/university-level mathematics / comp-sci course in algorithms & data structures, usually only a 3 credit, 200-level course, isn't really asking too much.
Then you'd know why your O(n^2) algorithm sucks on any dataset larger than a toy without having to be scolded.
There's 10,000 shades of gray between not knowing shit other than sort() and having a PhD. Use some common sense.