Timed assessment - what does it try to find out?

This heading is eye-catching, especially to a Maths teacher!
It came from the post at edutopia: Tips for Tackling Timed Tests and Math Anxiety

It started by explaining the drawbacks of "timed assessment" and subsequently putting in some suggestions.

Indeed, "timed assessment" was something we were subjected to, all this while - not just in Mathematics, but also other subjects. It goes back to the rationale of such assessment - and of course, these days, more would discuss the purpose of assessment, which has evolved from Assessment of Learning to Assessment for Learning.

Would you associate "Timed Assessment" more with "AoL" or "AfL"?

Timed assessment is widely used for placement purpose, though some "major assessments" include other components like coursework or core assignments to be completed over a given period of time (e.g. those involves some research or experiment to be carried out).

Instead of focusing on the concerns arises from timed assessment,  perhaps we can look at its purpose from another perspective?

It is no doubt that timed assessment causes stress the candidates as they are expected to demonstrate what they know within a limited time and psychologically, it creates a tension in how the brain processes data. One's heart pumps faster as it gets closer to the end time, haven't we experienced that before?

While I have not find out more (from any academic/ research papers) on this area, based on experience and reflection over these years, I think timed assessment has its merits. One of its "use" is to help us determine how well one has understood the concepts and being able to  apply what he/ she has understood in a fluent manner, which is also a demonstration on the degree of mastery (or proficiently)! It comes with two core elements: Understanding/ Mastery + Effort
(with the assumption that one needs to put in effort for what's learnt to stay!)

In other words, students could have understood what was going on in the class, and even able to articulate deeper understanding. However, when one lacks the practice or do not have enough rounds to rehearse the use, while he/ she might be able to retain and therefore able to 'retrieve' the necessary knowledge and skill to process the task in the timed assessment. In other words, he/ she would need more time to do so compared to another one of the same capacity but have put in the effort to ensure internalise the knowledge and skills.

Given that 'limiting' factor that adds to the tension/ stress, this student would not be able to complete the task as quickly as his peer who is of the same ability but has put in the effort to practice, rehearse and internalise.

That, I think, based on experience, accounts for most instances when students usually claim they do not have enough time to complete the paper!

一分耕耘，一分收获
This is not about finding out who knows, who doesn't know as any form of assessment would be able to do this.
I think...
It is about differentiating who learns better and shows the potential being able to extent learning further.