Can you do FUE (or multiple sessions) and then do FUT if you run out of donor grafts with FUE?

In my opinion, if you really want to maximize your results and keep your hair as it is I would start on finasteride 1 mg per day. Then go for a decent size FUE  since you wear your hair short and be done with it. If you need more in the future then you will have more. Many people have more than one surgery. 

There is only a finite number of donor hair you have.  FUE and FUT are just one way to harvest hairs.  If you want to keep your hair short, FUT will not be your best choice.

It is possible to have a few FUE sessions followed by an FUT procedure if there is an abundance of donor hair to work with, however, we all have a limited supply of donor hairs in our lifetime. Be leery of doctors who convince you this is possible without a proper consultation. If you do not have an adequate amount of donor hair, 3 or 4 surgeries is not possible without leaving scars or baldness at the donor zone.
If you'd like to keep your hair short, I would recommend starting with medical management to keep and protect the hair you have in conjunction with an FUE hair transplant. I have an excellent medical management program including GroMD Hair Loss Prevention Shampoo which will put a halt to further hair loss. 
It would be best to see a surgeon(s) for an in-person consultation. That way we can evaluate the scalp and discuss your options. We have several offices conveniently located in Orange County and Beverly Hills. 

The answer to this question truly varies patient to patient depending on the donor area + scalp characteristics. If you have the right donor area + scalp for the process, then yes it is possible to do more than one FUE to achieve the desired number of grafts. Generally it is recommended that you wait at least 8-10 months before having another hair-transplant after the first. The best thing to do would be to book a consultation so that you can get your precise hair-loss treatment solutions according to your hair specifically, and answer any further questions.

How much grafts do we need to cover the bald area ? How dense and large your donor site ? What i s the grading of baldness? It is better to see your photos  in order to understand the problem you have, treatment methods and/or estimate how much graft do we need to cover area a. So, I would like to request  you to send your photos. 

A great first step would be an online consultation. Often you can submit photos to top hair restoration surgeons for a complimentary evaluation. This should help lead you in the right direction. Having multiple consultations with different doctors cannot hurt. 

Thank you for your question. Most patients can undergo 2-3 FUE procedures depending on the number of follicles harvested with each procedure and the size and density of your donor area. Progression of hair loss is always a concern and I strongly recommend all candidates for a hair restoration procedure to take steps to preserve and enhance their remaining hair follicles. Some of the options include finasteride, minoxidil, low level laser therapy, PRP, and topcial products directed toward inhibiting DHT levels and promoting hair growth.The yield from an FUT procedure will be reduced following FUE as the hair density in the strip will have been reduced.I hope this was helpful - Dr. Moore.

It depends on the number of grafts that needs to be done at each session. Donor area thinning and depletion is one of the draw backs from doing multiple FUE procedures. 

Everyone has a limited number of donor hairs and your donor area must be measured so that you can determine how many grafts you have as a potential for FUE and/or strip surgery. As it turns out, half of the potential donor area can often be used for FUE, anything above that should be treated with a strip surgery, If you push the FU"E numbers very high, you can develop balding in the donor area.  See below