Our intent with suggesting hours on timesheets is that your team can see their budget of time for the week and try to work according to the plan. We don't have current plans to change this logic as the suggested entries helps the team understand their assignment expectation.
However, some teams find that the plan is often very different from the time tracked. In this case, we recommend that people use the “Clear Suggestions” feature to start from a blank time card each week.
It is not possible to turn off time suggestions for all users in your account.