Is fast fashion ever worth buying?
Rarely - it fails on cost per wear. The exception: true one-occasion items and trend tests under $30.
Run the numbers instead of the price tag. A $12 item worn 5 times costs $2.40 per wear; a $45 item worn 200 times costs $0.23. Fast fashion only wins when the wear count is inherently low by design: a costume-party piece, a trend you are testing before investing, or a stopgap (the emergency white shirt before a trip). Even then, secondhand usually matches the price with better quality. The category where fast fashion is structurally indefensible is basics - the exact items where cost per wear matters most, because you wear them constantly and their failure is guaranteed. Buy your tees, jeans, and knits well; they are the cheapest clothes you will ever own.