ExampleService.cs

internal interface IExampleService
{
    Task VeryImportantWorkAsync(int additionalSecondsToWait);
}

internal sealed class ExampleService : IExampleService
{
    private readonly IImportantDataProvider _dataProvider;

    public ExampleService(IImportantDataProvider dataProvider)
    {
        _dataProvider = dataProvider;
    }

    /// <inheritdoc />
    public async Task VeryImportantWorkAsync(int additionalSecondsToWait)
    {
        var timeToWait = _dataProvider.GetTimeToWait() + TimeSpan.FromSeconds(additionalSecondsToWait);
        await Task.Delay(timeToWait);
    }
}