Churn, Conversion and pLTV/UA are the three most critical problems that most companies have.
Churn – your consumers/customers leave after a while for some unknown reason. You can speculate (hypothesis) but you are not sure why
Conversion – Your consumers/customers buy your products. You are happy and you think that you know why and what levers to pull, but no matter what you do, your numbers do not change dramatically or at all.
LTV and UA – Acquiring consumers/customers has a cost. You think you have a positive ROI on your campaigns, but you are not sure until 30, 60, 90, 180 days out when you might (or might not) know whom of those users converted and how much the spent. Some of those users did not spend enough to have a positive ROI, thus, your campaigns we far from profitable and not optimized.