Methamphetamine increasing exam performance

[Rogue]

Hypothetically speaking, say a person had university/college exams coming up soon. These exams would last approximately 3 hours and the person in question, whilst not having ADHD or a similar condition, occasionally had the problem of a wandering mind whilst in lengthy test conditions. This person might have occasionally used methamphetamine recreationally.

Would the usage of small amounts of methamphetamine (powder, not crystal form) actually improve performance by means of increased concentration?

In your opinion, would the benefits outweigh the drawbacks?

In such a situation, what sort of dosage would be required to gain the desired effects?

Does anyone have any hypothetical annecdotes regarding methamphetamine use in tested conditions?

Your advice and comments would be greatly appreciated.