Is it safe to have arm and stomach liposuction with a breast fat transfer and a labiaplasty all done in one session?

This is an excellent question. Generally, the risk of complications like blood clots and anesthesia related complications go up the longer the surgery. This risks are further compounded if you have medical problems, family history of certain conditions, take certain medications and if you are a smoker. As such, your individual risk factors and how long it would take the operative surgeon to do the case factor into the right answer, also taking into account you and your surgeon's comfort level with doing all in one stage.
In terms of healing time, having multiple areas operated on will not significantly impact your healing abilities, but it will make recovery a little more uncomfortable. As long as you are healthy and your surgeon is comfortable to do both surgeries in on setting, this is a reasonable option. Make sure to discuss your personal risk factors with your surgeon to see if you are a safe candidate for this. Hope this helps.

Many factors enter into the determination of patient safety for surgery. These include age, health status, current medications, habits such as smoking, and estimated length of the planned procedure. Your surgeon will make recommendations during a consultation, after obtaining information on your history and conducting a physical examination.

If your surgeon performs all these procedures and thinks that you are medically stable to do all these procedures at the same time, then they can be done together. Longer surgery time does increase risks, especially like blood clots and pneumonia.