In most situations, Linnea’s gameplay is as simple as tapping her Skill then immediately swapping out. Her Burst is only really used for its healing. It can be used as an emergency button, or simply substitute her Skill in rotations when available at the cost of taking a bit more field time.
Note that it is possible for Linnea to swap out after finishing the taps on her Skill but before the damage is applied. This causes Linnea to take slightly less field time when using the nuke at the cost of losing out on some buffs like Illuga’s Burst or her own second Ascension passive.