My dr said they'll only do 1 vein per day and an ultrasound after each visit. Does this make any sense? Thank you!

Like with most things in medicine.  Treatment plans should be tailored to the individual patient.  While it is possible to do more than one ablation at at time, there may be reasons why doing one at a time is best in your case.  The more procedures that are done in one day, the higher the risks of clotting or other complications.  Also, you can expect to have some pain after each procedure which is generally worse the first few days, so separating the treatments can minimize some of the discomfort and ensure that you will be able to walk enough afterwards. If you are too sedentary because of too much pain resulting from multiple large veins treated on one day, your risk of clotting rises.  It is also important to do a follow up ultrasound within several days after each ablation.  Having said all this, the follow up ultrasound visits could be easily combined with the next vein to be treated, as long the follow up shows no complications there is no reason why your next ablation could not be done on that same visit.  If there are any complications,then the procedure would be cancelled.  While this may be an inconvenience for the practice, it is a reasonable accommodation for the patient.  And yes, you have the right to request your records!

The common practice is to do one vein at a time and is usually followed by an ultrasound. If there is an accessory vein that needs treatment then that can be combined with GSV ablation. I have treated SSVs on both legs in one setting if needed. So overall depends on the patient and surgeon comfort level. Its hard to treat GSV  and SSV at same time but can be done. 

It is common to have different veins treated on different days. There are a variety of reasons for this. An ultrasound following the procedure is also appropriate. However, 5 veins on 5 separate days seems like a bit much, without knowing all of the specific details.  In most instances, any veins beyond 4 that need to be treated are accessory veins and they can often be treated at the same setting as the other veins. It is important to remember that every case is different and your treating doctor should be willing to answer questions related to your specific case.  

Though there are patients who need four and five veins done, these are in the minority. If you are remotely uncomfortable with your treatment plan, invest in your piece of mind by getting a second opinion. Some physicians are less knowledgeable and/or experienced and may treat veins unnecessarily. I see many patients for second opinions - some of whom have been told they need as many as eight veins treated - and find they have normal circulation and only need a cosmetic treatment.

One of the limitations in performing vein closure by either EVLT or Radiofrequency ablation is the amount of local anesthesia that can safely be used at a single setting.  Because of the need to inject anesthetic around the entire length of the vein, a large volume may be required. 
Positioning is another issue. It is not possible to do the great saphenous vein treatment at the same time as the small saphenous vein treatment due to their location in the leg, the great being in the front and inside while the small is in the back of the calf.
Normally, the when the great saphenous vein is closed, an anterior or posterior accessory vein can also be closed. However, some insurance companies will not cover both procedures at the same time and require a time internal.
I personally have done about 1000 vein closures by radiofrequency ablation, and think that 10 vein closures seems quite high. Always good to get a second opinion if you have any questions.  See a vascular surgeon with a vein practice.