RQ: Gokujou Parodius Extends + PS1/SAT differences

[Kollision]

I've been playing Gokujou Parodious on and off lately, and I still don't understand why the extends don't always come.
At first I thought it was character-related, but then I played multiple credits with different characters and noticed it's not the case.
Sometimes I get them at 100K/300K, sometimes at 200K, and sometimes no extend at all.

Does anybody know the logic behind this?
Is there a way to get the extends in every credit?

I'm playing the PS1 version by the way.

[Kollision]

Okay then.
From my observations and a few sources I found online it seems the PS1 version of GokuParo is in real disadvantage when compared with the Saturn port.

Other than the absence of the aforementioned extend routine bug, I have also noticed that on the Saturn the game has richer sound effects and less slowdown (or slowdown that's closer to MAME - candy stage on full power being a very good base for comparison).
Besides, loading times are shorter, the save function is automatic and the game allows you to choose between arcade and fullscreen aspect ratios (PS1 seems to be locked at arcade ratio, although slightly different from the Saturn's).

[Bloodreign]

Isn't it this game, or the original Parodius that also had broken scores for the bells? I know this and the original arcade Parodius Da were on the same disc, perhaps they shared problems even if the problems are a bit different.

[Kollision]

Indeed the scoring in Parodius Da in both ports (SAT, PS1) is broken, with the game itself being easier.

Goku Paro on the Saturn, however, is just like MAME from what I could tell.
And has almost no slowdown. And has two extends per credit all the time (at 100K and 300K).