Apologies. You are right that my post was poorly worded. And the use of "busy days", "big chance" and "most" without quantitative support is a bit meaningless.

I tend to be an optimist and see the glass half full rather than half empty.

But when a flight is full, it is full and unless last minute cancellation (or missed connection) there is little hope, even for an "old" pilot. And we all know holiday periods when flights are full and possibly overbooked.
But with a little planning and flexibility (like when there are many daily flights), there is a very good chance on most other days as you are number one in priority (because you are an "old" pilot). It is never 100% and I have no statistics.