The alternative test is paying 90% of the current year's liability, which requires predicting a trading year you cannot predict. The prior-year test is knowable in January, which is why most traders use it.
The 110% figure applies where prior-year adjusted gross income exceeded a threshold. Payments must also be spread across the quarters; a single large payment in January does not cure earlier shortfalls unless the annualised method supports it.
Withholding is treated as paid evenly through the year regardless of when it happened, so increasing withholding from a salary late in the year can retroactively fix an underpayment that estimated payments cannot.
General information for the United States, not tax advice. Rules change and depend on your circumstances; verify with a professional.
Related: estimated-quarterly-taxes, trader-tax-status, self-employment-tax-prop-payouts, irs, schedule-c-trading-business