What is the toughest part about regulatory affairs?

To deal with standards time for registration process , in addition if your company in hurry to register a product & company R& D made a mistake needs for RE-SUBMMSION

To me it is the periodic amendments and updates to the regulatory pathways and procedures which can be time consuming and in a way costly.

Most toughest part is changes in procedure and requirement frequently.
which increases the time of registration and more documention and effort needed.

Being able to fulfill each market's regulations within the specific time scheduled in RA plan

Dealing with emerging regulations and new regulators.

The toughest part of Regulatory Affairs would be to ensure your Organisation does not fall into the bad books of the Regulator and to achieve that you have to be well versed with all the Regulatory Guidelines and instructions that pop up from time to time.