I’m presuming based on current evidence that all other timers work by giving an exact time display, even POS which can be variable, so most likely option is that we see the exact timer., I flagged CCP in an earlier post asking to clarify exactly The RNG timer can totally make a difference, I agree. But you are forgetting that you no longer have the vulnerability window. You now pick an exact time of day & week. There is no 6 hour window on your Fortizar.
Shield is always vulnerable, armour timer is 1-2 days after someone hits your shield at your exact time +/- 2 hours. Hull timer is your exact day & time +/- 2 hours. So the window for the timer you are talking about isn’t as big as you think.
Actually someone can shut you down for nearly 2 weeks in highsec. If you have say a Saturday timer, if they do the armour timer on Tuesday, then +5 days takes you to Sunday, which means the next allowed hull timer is 12 days away. Then even if they don’t turn up you get Sunday/Monday, they shield reinforce you Monday and then armour reinforce you Tuesday again. And expecting high sec groups or even small lowsec or wh groups to be able to form a fleet 7 days a week isn’t likely.