An initial grant that vests over four years is not the same as being paid in equity every year. Some employers refresh on a schedule. Some refresh only for a promotion. Some never do, and the grant you see is the grant you get. This page leads with that question. The sample notes say a refresh has not been described. Keep that sentence until someone describes one.
How to ask
Ask whether refresh grants happen, what they depend on, and whether this offer includes anything beyond the initial grant. Ask for the typical range if they have one, and for whether unvested refresh disappears when you leave. You are collecting facts, not accusing them of hiding pay.
If there is no refresh, your target has to work on base, bonus, and the initial grant alone. Do not spread a single grant across imaginary future years to make the offer look larger. The yearly value box is for a number you believe, not for a hope.
If they offer a refresh promise, ask for the timing in writing when you can. “We usually do this” is not a grant. A sentence in the offer letter, or a compensation plan they will send, is.
Questions
Is it rude to ask about refreshes before I join?
No. It is how you tell a four-year grant from an annual one. Ask it the way you would ask about the bonus plan.