Hinalover, you do the shift to bear form & lacerate while your energy is regenerating. This is something i actually did on my guilds first Algalon kill so i remained right behind the tanks on threat, It was so i could pick him up if one of the tanks happened to die.
The only thing you lose if done right is a few auto attacks and at that point in time i would also mangle in bear(had it glyphed so it was 18 seconds) so i had the extra energy for shreds in cat
tbh i saw a slight difference in my dps while doing that but it made things more complicated
Every cycle i lost ~4 Auto attacks in cat but gained 4 ticks of lacerate, 1 auto attack in bear, the damage of bear mangle and 35 energy from no having to use cat mangle