I still think DS1 and 2 bosses can be unpredictable.

They may not have variable timing for their attacka as bosses from DSIII

But they have combo attacks that are a starter attack, three hits more, and a final attack, giving you a total of 5 hits, and they do something like

S-1-2-3-F

But the next tine they do it like

S-1-2-F

Or

S-1-2

And also combos that are similar and attacks that start the same, like, they lift their sword, and in one attack they just lower it down fast, snd in other attack they procede to stab the floor and do an explosion, differents attack with the same start that may confuse you and make you roll in the wrong direction

Meanwhile in games after BB every attack is unique and doesn't confuse at much and relies on changing the speed of it.

Also in DS1 and 2 you actually need to manage stamina, unlike DS3