I read somewhere that the negative battery cable should be disconnected, then reconnnected to reset the ECU (and to let the engine run for about 20 minutes), so the ECU can "learn" with the new coil packs installed.

Is this what I should do after installing new coil packs?

 

R&R of the coil packs requires ignition to be off but battery don't have to be disconnected (I did inspection of mine with battery connected)
Disconnecting battery for whatever reason requires to do the idle learning (I did not do it though).
What are your symptoms?

 

I've disconnected my battery several times (2007 Fit), for various reasons. I have never done a "learn". The ECU "learns" as it goes.

 

I was getting a check engine light every now and then for cylinder 4 misfire, and when I started engine I would feel the engine intermittently shake, or stutter, plus the shifting wasn't shifting pretty smooth.

I just replaced the coil packs with Hitachi, and the shifting is smoother I noticed, and seems like not as much shake/stutter. I noticed that the coil packs I replaced, looked like aftermarket brand, and 2 coil packs looked like part of the black boot had melted away from the boot.