Bilateral Total knee replacement: one at a time or both at once ?

I am a spinal cord rehab physio who hasn't worked with TKR/THRs for years. My mother has severe OA in both knees and has been offered by her surgeon to have both knees replaced in the same surgery. The setting is a hospital where physios are quite involved before/after surgery, they do a pre-op assessment, etc. I am wondering what physios who work in this field think - is it better to have both knees operated on at the same time or is it better to do two separate surgeries ?

The surgeon leans towards one surgery mainly because it would involve less risks of infection. However, I am anticipating a more difficult rehab process. But I could be wrong.

Any input is welcome. Thank you in advance and have a good day.