Looking through the threads where file size is discussed, I am wondering how big is a big file?

I recently inherited an stp file for editing. It was about 500KB. Nothing complicated. I added some embossed 3D lettering (6 letters) some booleans and fillet ALL the edges of the letters. So a lot of fillets. The exported file was 3.6MB, which surprised me. Especially since it causes a few problems, emailing for one.

Is this a reasonable sized file, or would it be considered big in engineering circles?

I did an experiment: import stp to MoI, then immediately export. File size went from 471KB to 729B. (I did the same in Alibre and the output file was even larger than that)

Even so, to my mind 3.6MB is pretty big.