Aikido is a series of exercises designed to give you mind body and spirit the opportunity to develop certain useful attributes.
To think that you are learning to counter wrist grabs when someone is grabbing your wrist, IMO, misses the point.
You are using the situation of someone grabbing your wrist as a training exercise to develop tools that can be applied to an infinite number of actions. First the static grab, then the grab with an approach, then the grab with what seems like a tackle...each time building on your ability to use aiki.
Techniques are limited. Aiki is not (idealy ofcourse
). Do I want to develop a limited number of techniques, or the ability to simply act? That decision will guide my training.