Jellytots it does depend on the quality of the blastocysts to some extent.
There is a correlation between their morphology (what they look like) and the rate of success.
Clinics will grade them. Initially they used letters, now they use numbers. Although a blastocyst that doesn't look so good can definitely make a baby, the chance is not so high.
My first fresh round resulted in two blastos. One graded Ab was put back in and resulted in biochemical.
At time of transfer we we're give a 60% chance of pregnancy.
An Ab/a was frozen but we had a failed thaw (about 30% of embryos fail to thaw)
Second round, two fresh both graded Bb. Given a 40% chance of success. BFN.
Third fresh, two Aa blastos transferred. Given 70% chance of success and if successful 50% chance of twins - BFP (twins).
The two on ice are graded Bb so less likely to be successful, but it depends on the quality frozen.
You could ask for a chat with the embryologist. I did and found it really helpful.