That would do it. Mythic+ has a different playstyle to it than a raid does as a general rule.
It does cost a lot of mana which is why you can’t (at the moment at least) spam it WoD style so you weave it with single target spells (myself I weave with healing wave, surging only if I need to) and then add your riptide/hst/healing rain on cd if people are going to stack in it. Also it will depend on the fight how much you do of one or the other, some fights are more suited to st spot healing than others.
Shamans do have some pretty awesome cd’s but as with everything, I find if you’re new to healing (same goes for dps for myself) get a flow and thusly sticking to more passive options is a wise thing to do whilst you grow more comfortable, the rest will mostly come with practice and time. No worries, do let me know how you get on and ask away if you have any more questions.