I have my 3 pulses bound to cntrl+1, 2 and 3 respectively. You have a very limited mana pool and twisting the chants mindlessly is generally not prudent. I still find myself rolling the chant keys after a slam pretty often, but this is objectively a bad decision and very lazy play. I'm still getting used to my keys and the Reaver has an absurd amount of qbinds to keep track of.
Your PBAE DD pulse doesn't have a huge radius, but it can still be used as an interrupt and to pop stealthers if you're lucky enough to see them as they inevitably attempt to add on any fight you are engaged in. As a damage ability it is basically useless, but it can provide a surprising amount of utility if you have it off of cooldown for the right moments.
Your damage debuff and absorb debuff are surprisingly powerful, but sometimes it is worth saving them for a few seconds to hit key targets. Either way you should always be applying them when you can, but be sure to cancel the last one (for example on a target that is slammed and can be killed in stun-- cntrl 1 [DD] - cntrl 3 [abs debuff] - cntrl 3 [cancel]) so you don't waste the extra power.
Tying into this concept it is very important to be judicious with the use of your instant shouts. Unless you absolutely need them to 100 to 0 a target you have slammed or you are positive you wont need them for the next thirty seconds, it is always better to save the LTs to use as an interrupt or for when they will actually heal you. The key with using these abilities properly is extracting as much utility as you possibly can from them. Interrupting an add or something like a thane after he slams, kites, and casts on you is far more valuable than just doing 120-180 damage on a slammed target while you're at full health.
The Reaver can be extremely successful when played as a faceroll class, and that is what most people tend to do, but there is a lot of nuance and decision making involved in getting the most out of it. Due to the sheer number of abilities and the extremely small time frame you have to use them when you're essentially swinging at cap speed the ceiling on the mechanics involved is incredibly high.