I just want to mention that as with a lot of things, there is sometimes a negative effect from the extreme at the other end. I saw this data a few years ago, but haven't had much luck Googling it again, so no links--sorry. But being in the state of charging is still more stressful on the battery than being in a resting or slow discharge state. So:
The general statement of "slower is better" is mostly correct, unless you get down to where the power is SO low that it blows out your charging time to 5X or 10X what you would normally do, and the battery is spending the majority of its time in a charging state. That builds up some wear on the battery too. So this is mainly to people where I see them talking about turning the amps down to 5 or 6 because they think slower is always better, and it's eventually not when you get down that low.