Well, there will be storage, as long as the form for each row has been submitted. The calc element always stores the value on submit.
What I don't know is if the values are valid. If they are computed against two static dates (like a "start" and "end" on the form), then they will be. If they are computed against "now" (so time between a "start" date on the form and the date/time "now" when displayed), and you have "Calc on save only" set to No (so they recalc when you show the list), then no, the values in the table won't be valid.
So what is the actual calc doing?
-- hugh