Is this necessary to shed hair after Hair Transplant?

Dear Ukboy,Thanks for your question.  This is one of the most confusing things about the entire hair transplant process.  It is true: following a hair restoration procedure, many of the follicles shed their hairs. Here is the reason why: unlike our nail beds, which make our fingernails for the duration of our lives without a break, hair follicles make hair in cycles. The timing of the cycles is as follows:Anagen (growing phase): 2-7 yearsCatagen (short phase before resting phase): 2-3 weeksTelogen (resting phase): 3-8 monthsAll humans are experiencing this at all times. A person with a full head of hair is shedding 50 to 100 hairs per day, and at the same time, 50 to 100 hairs are coming out of the resting phase (eg: Telogen) and producing more hairs.The stress of a hair transplant procedure that is placed on each and every individual follicle transplanted can trigger some or all of the follicles to come out of the anagen phase of growth and enter the catagen phase, followed by 3-8 months of the telogen phase when the follicle remains alive but produces no hair. The hairs re-enter the anagen, or growing phase, after 3-8 months, producing new hair. The hair will typically start to thicken and return in months 3-8 following the procedure. It’s important to understand that every day is going to be a little different as the hair grows in, and one can’t really say that one has their “final results” until 11 or 12 months following their procedure.

Shock loss is due to the loss of normal hair whether it is from donor site or recipient area.  It can occur with both FUE and strip procedures.  Usually if it occurs it will take place in the recipient area.  
Shock loss from hair transplant can occur due to the following:
Anesthesia-  excessively long procedures taking longer than 12 hours can induce shock loss more likely.  the repeated use of lidocaine, marcaine, and perhaps most importantly epinephrine can affect nourishment of the hair
Traumatic harvest-  In strip surgery, traumatic harvest can induce shock loss.  
Recipient area trauma- during the incision making process the hairs are either crushed or cut and damaged during the process.
Ways to minimize shock loss are as follows:
Improve recipient bed and donor area environment.  Make your recipient environment improved by addition of growth factors and/or PRP to help reduce incidence of shock loss to native hairs.
Use of Rogaine and Propecia- can help miniaturized hair become more stable and less likely to fall out during procedure
9xRobotArtas-  The latest version of the robot can make recipient sites and can determine angle of existing hair and help ensure that the angle will not damage existing hair.  Especially helpful in patients where you are transplanting hair to create density
Minimize anesthesia time and procedure time- We limit number of grafts to a safe number per session.  Extended anesthesia periods and harvest times can cause patients to have a higher chance of shock loss.  The 9x Robot harvests between 1000-1500 grafts per hour making it superior to previous additions and traditional FUE approaches.
Best, 
Anil Shah

No, it is not necessary to shed after a hair transplant surgery.  But in most cases you will shed.  It takes 6 to 12 months to see results after surgery.  Results of surgery is not dependent on shedding or any one single factor.  Results depend on how well your surgery went in general.