For posts such as Kharidar, Nayab Subba and Section Officer, the Public Service Commission conducts a computer skill test in the final stage alongside the interview. Those marks are added to your total, which means a candidate who prepared for months on the written papers can still slip several ranks over a typing passage.
The pattern repeats every cycle. Candidates treat typing as something to sort out later, the result is published, and three weeks is not enough to build muscle memory that normally takes two months. Typing is not knowledge you can revise the night before - it is a physical skill, and the only input that moves it is repetition spread across days.
The good news is that the requirement is modest and completely reachable. Twenty to thirty words per minute is a realistic target for anyone who practises consistently for a few weeks, and unlike general knowledge, typing marks are fully within your control.