Two tools, and a date in your calendar

Why people who do this for a living keep more than one

Disagreement is a working alarm. Ask two different models the same factual question — a tax threshold, a drug interaction, a formula, a legal citation — and when they disagree, something is wrong and you should go and look. This is the practical value, and it is large.

Be careful about the other direction. Agreement is much weaker evidence than it feels. These models read overlapping piles of the same internet, so they repeat the same common mistakes in unison. Two models agreeing means they did not disagree. That is all.

Different jobs, different fits. One writes prose you do not have to rewrite. Another is better at picking apart a spreadsheet. A third lives in your editor and sees your whole project. This is not brand loyalty, it is using the right tool.

Insurance. Providers have outages. Caps hit at the worst possible hour. A second tool costs nothing to keep ready.

It keeps your thinking clear. Use one tool only, and you start mistaking its habits for the nature of AI itself. Its refusals become "AI can't do that." Its style becomes "how AI writes." Neither is true, and you only find that out by using something else.

It keeps you free to leave. If your whole workflow is built on one company's memory, projects and integrations, the price rise arrives and you pay it.

A setup that costs almost nothing

One paid plan, chosen by the test in lesson four. Two free tiers from different companies for second opinions. One small local model for anything confidential or offline.

Use the paid one by default. Do not switch constantly — jumping between tools for every task is real cost for no gain. Reach for the second when the answer matters and you cannot check it yourself.

The whole re-evaluation method

Open your calendar. Create a 30-minute appointment. Repeat it every six months. That is the method.

When it comes round:

1. 1Run your five prompts — the file you made in lesson two — on your current tool and on two rivals' free tiers. Twenty minutes.
2. 2Open the data settings page and read it again. Things change quietly.
3. 3Check whether the price or the caps have moved, in your currency.
4. 4Check which model your plan is actually serving now. It may have a new name.
5. 5Check whether an open model has caught up on your particular task. For summarizing and extraction, it very likely has.

Then decide, and close the laptop. Half an hour, twice a year, and you never again choose a tool because of something you read on a Tuesday.

What will have changed, and what will not

In six months, expect: prices per token down again, context windows longer, free tiers moved in both directions, at least one model you like deprecated, and one open model doing something people said only frontier models could do. Every specific number in this course has a shelf life measured in months. That is not a flaw in the course, it is the state of the field, and anyone who writes as though their comparison is permanent is selling something.

What will not have changed: models are fluent when they are wrong, and fluency is not a reliability signal. The product layer decides your experience more than the leaderboard does. What leaves your machine is the thing to check first. And your own five prompts still tell you more than any review.

You now have the method. The tools will keep moving; you know how to re-check them.