dotnet.core Asp.net Async / await everywhere?

I recently began working in a new company. They have an ASP.NET Core 3.1 application hosted in IIS, which takes API calls from an angular app. They used async/await literally "everywhere": Methods in the ASP.NET controllers have signatures like public async Task<IActionResult> Foo(), all DB queries are made async, all calls to external APIs anyways (which I kind of understand).

So instead of simply

[HttpPost("api/ignorableDepartment")]
public IActionResult Add([FromBody] AddIgnorableDepartmentRequest model)
{
  return _ignorableGroupManager
          .Add(model)
          .ToResult();
}

the code now reads

[HttpPost("api/ignorableDepartment")]
public async Task<IActionResult> AddAsync([FromBody] AddIgnorableDepartmentRequest model)
{
    return await _ignorableGroupManager
                 .AddAsync(model)
                 .ToResultAsync()
                 .ConfigureAwait(false);
}

This application is only used by 1-2 people at the same time, and the calls in the method above would take 1ms at most.

In the past I would only use async/await if the processing is expected to last like 1 second or more, and in all other cases, I would just rely on IIS to take care of spreading multiple requests across threads/cores.

Did I just miss something in the past years, and this is the new way to develop? Or is that just overkill?

Updated information to answer questions in the comments

• AddAsync adds the model to the database. So I guess it's ok
• ToResultAsync() looks as follows (which makes no sense IMHO, since the controller method returns a Task<IActionResult> anyway. It also doesn't parse the passed information in any way, which a To... method would indicate)

public static async Task<IActionResult> ToResultAsync(this Task task)
{
    if (task == null)
    {
        throw new ArgumentNullException(nameof(task));
    }

    await task.ConfigureAwait(false);
    return new OkObjectResult(ResultResponse.Success);
}