Input < Product Value < Output.

This is the equation. When you quote on the input - that's the time you need to do the job, you multiply your rate for the weeks/days/hours, plus maybe some other expenses. This is the so-called "Hours and materials".

When you quote on the output, you take in consideration the overall value/gains you client will make by your work. This is called "value-based" pricing.

This equation is unbreakable, if your input is grater than the client output (ROI), something is very wrong, or completely illegal.

Some says value-based pricing is the holy grail for pricing anything, but if you're smart enough, you already understood that, based on circumstances, sometimes it makes more sense to quote on the input, other times on the output. Just do the math.

This may be a classic example of "value-based" pricing. It doesn't matter how long you take to make a static HTML page (input), the client overall project budget is probably over $100K (as stated by op), it's totally ok for them to invest ~20% of it to make sure it delivers on time and by specs.

You are describing leverage.

As a contractor hourly work is often relationship suicide every 2-3 years when your value is questioned no matter how great the baseline.

To move towards value based pricing, and not splitting hairs on time and hours, by billing minimum half or full days with the understanding not much gets done less.

Of course value based pricing, at a weekly or monthly retainer is the next step.

I’ve done all of the above.

The client doesn’t care if it’s an html page it’s the value it creates or enables.

Rarely do most businesses wake up wanting to buy more tech and software dev, they have business problems or outcomes to solve.

If the solution was a single html page I wouldn’t even talk to the client in terms of an html page or not.