you can make macros that use "on use" trinkets at the same time as frequently used abilities that line up well with the trinket effect.
One of my trinkets has an "on use" that gives me a bunch of strength and it's on a minute cooldown, just like bloodbath, so I macro in bloodbath and the trinket into bloodthirst and they're always up whenever I need them.
Now, this can be bad if you need to initiate a burn phase and pop all cooldowns and these things are off cooldown, so instead of macroing them into bloodthrist you could just make a bloodbath/trinket macro. I have a macro that casts skull banner and recklessness at the sametime, for example, that I use for burn phases.
This doesn't eliminate the number of abilities you use both does minimize the need to micromanage abilities.
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