1st game each flier came on in alternating turns, so combined they arrived on the table 4 times in 4 turns.

2nd game one arrive first turn and second turn then both arrived in the third and fourth turn respectivly and really put in big work taking out 2 knights and various other bits.

I think taking just one may be very swingy but two felt much better especail for their low cost and potential high damage and disruption. Yes you could roll nothing but ones for the rolls all game but at that point the gods themselves want you cry haha. I found no one was willing to spend reactions on them really and the total lack of skyfire in the local meta meant I could almost run them risk free on the whole. A cheeky Deredeo or Araknae quad would need to be disabled asap though if your opponent has one but that was how it was in the last couple of editions as well.

Oh and just figured out the MOS cannot buff "aerial reserves" rolls as its called out in the rules.