Cases allow you to classify your data. Instead of just coding text about a person, you can create a "Case" for that person and assign attributes (Age: 35, Gender: Female, Location: New York). This allows for powerful comparison queries later.
Stop coding every 30 minutes and write a memo. What are you noticing? Are two nodes overlapping? Do you think "Stress" actually means different things to different people? Record these thoughts inside NVivo. It saves you from forgetting your "aha!" moments. Cases allow you to classify your data