I use sky flats. My observatory uses ACP and ACP has dark and flats acquisition scripts that take all the guess work out - it's automated and the results are just fine from my precision photometric work.
Basically the script defines what types of flats you want (ie filters) and how many flat images for each filter you want. It then points the scope and starts imaging and continues until it gets the flats or it gets too dark. The script decides if the image is suited by looking at the max pixel values and either accepts of rejects the flat and tries again.
Hey, I like to do things the easy way - sleep nights
Cheers