Number of lambda calls when called many nested calls are executed

If I call one lambda function with one request, but within that function, there are three calls made to different functions then would this count as 4 calls or is it just one call since its based on one request?

So if the count is 4 then (from economic stand point) wouldnt it be better if one writes one long function instead of many small functions, despite it being ill advised from economic stand point?