My steps are set to  (just 1 minute) and my graduating interval to 7 days. So when I see a study a card for the first time and grade as as “GOOD”、I should see it again in exactly 7 days.
For test’s sake、I’ve disabled all my add-ons and made a new profile with 15 cards、which I’ve censored、as shown above. Even though I’ve marked all of these never-studied cards as “GOOD” today (November 2nd)、they are due to different days: 3 one of them are due November 7th (5 days from now、not 7 as it should)、only 2 of them are due November 9th、7 days from now.
Is this normal? If yes、how can I get all of them to show up again exactly 7 days from now?
P.S. I’ve read the whole manual、read articles online and recently learnt HTML and CSS in order to use the software. My decks are 100% ready、this is the only issue I cannot figure out on my own. I’ve also tried the V2 scheduler and tinkered with other deck options、but cards are always due to different days for some reason.
One thing that isn’t mentioned in the manual is the Fuzz Factor. You can read about it on Deck Options Explained.
As far as I know, the only way to have exact intervals (apart from add-ons) is to use learning steps.
cards in learning also have some randomization: in the v1 scheduler it was up to an additional 25% (which could be very long if you run multi-day learning steps). In the v2 scheduler it’s capped at 5 minutes, see here.
for review cards the code that fuzzes the interval is in this function.
Thanks for the solution. I will make an official suggestion so that the Fuzz Factor will be explained in the manual.
Thank you for the answer. I will mark @Rumo 's answer as the solution because they have provided a link to the detailed explanation、but your answer is also very helpful and complements his. Appreciate the help.