BULK Butler allows you to benefit from all the power of PDF Butler in terms of personalization, branding, structure, content, multi-language, multi-currency, complex data structures, … while scheduling to generates big amounts of documents:
At the time you need it: process every night, every week, every month or a one-shot. Just schedule directly in Salesforce.com
In the timeframe you need it: your processes might require that the documents, eg invoices, are generated is specific period. Count on the scaling of BULK Butler in your process.