Budgets and budget cycles can sometimes interfere with making wise training investments. With training credits, you can purchase training now (when you have the budget) and schedule it later (when you need the training).
Purchasing for yourself? You don't have to know what, when, or where you will take training yet. Managers don't even have to know who will be trained yet. Spend the budget while you have it, and schedule the training later when you need it.