A name moves $2\%$ a day. What is a one-standard-deviation move over a five-day week, in per cent?

Variance adds over independent periods, so volatility scales with $\sqrt{t}$, not with $t$. Five days therefore gives $2\% \times \sqrt{5} \approx 2\% \times 2.236 = 4.47\%$. Multiplying by five instead would give $10\%$, which overstates the move by more than double and is the standard error. The same square root is why a one-year option has roughly $3.5$ times the vega of a one-month one, and why doubling your sample only cuts an estimation error by $30\%$.

Takeaway: Scale volatility by the square root of time, never by time.