If you've ever played a DPS class, you're familiar with working with stats with caps. You have to worry about hit and expertise caps, and there have even been haste and crit caps, too. While playing the min-max game with these stats can be entertaining, healers rarely have to worry about stat caps. Our primary stats, intellect and spirit, don't have any caps to speak of. We do have a few haste breakpoints where we get bonus Holy Radiance ticks, but haste and mastery don't have any hard caps that we can reach. We can pick up any healing stat without worrying about having too much of any given stat.
Instead of dealing with stat caps, healers deal with spell caps. DPS classes have an optimal system or rotation that they follow, but healers have several spell options they can choose from. Each spell has its own limitations, and knowing when to use what spell is a key part of playing a healer successfully. Holy paladins are especially familiar with these issues, as our spells tend to be in flux nearly even patch. Learning how to work around each spell's strengths and weaknesses will ensure that you always use the right tool for the job.