Just want to note about probability trick by SG that make us think that the chance is better by expectation calculation (which is a correct calculation btw). The other key factor against players in this case is “variance calculation” which is so bad in Harvest Festival.
To simplify cases, consider the two following odds having the same expectation = 2
Case1 : 50% chance to draw-1, and 50% chance to (bonus) draw-3
Case2: 99.9% chance to draw-1 and .1% chance to (bonus) draw-1001
We can see that on both cases, the expectation is 2, but Case2 is so bad that if you don’t summon like 1,000 times, it is very less likely that you will get the bonus draw, so practical expectation of Case2 is just 1 (against theoretical expectation of 2).
This is because the variance of Case2 is so much higher than Case1. The same is true for Harvest Festival Summon (if you looks at the odd).
So practically, if we are not super lucky, normal players can expect +3 or +4 bonus draw to happen for 10 or 30 summons.
Do not expect +9 or +8 bonus draw with 0.1% and 0.2% odds
And practical expectation in this case is considerably lower than BlackFriday (also more expensive).
Some practical evidence can be seen with Aeon Gaming 15k Gems summons here and you can see how many bonus draws is practical
(TLDR: 24-noluck, 6-of-bonus+1, so 36 from 30 summons)