Maximum number of lines on a GEC and BA.

Is there a limit to how many lines you can have on a GEC or a BA? 

The maximum number of lines recommended is 200 total, or 100 on each side (from/to). If your document has many more lines than this, it is likely to get stuck when you try to save or submit, or when your approver tries to take action.

Why is this? 

Check the General Ledger Pending entries tab after you save your document, and you'll notice there are many more lines there. Each line in your document generates additional lines reflecting processes that take place to complete the transaction.