The rule I was taught when programming was "Make every CREATE or DELETE action deliberate (at least two clicks with no defaults!), so as to reduce potential issues from accidental clicks! Especially when sequential numbering systems can be affected!" This is even MORE important now that people are using smartphones, tablets and touch screens in general! The possibility of a mis-click is quite high!
For example, Invoices and Estimates can be created with a single click and no line items! This can really throw off numbering sequences and accounting flags. I suggest implementing a "cart", you can add items to it and then create either an invoice or estimate from that. Seems like a more logical and accounting friendly way of doing things! There's a reason why QuickBooks and those programs don't allow blank invoices, all invoices need at least one line item, even if it is just a temporary placeholder!
Also assets can be deleted without any confirmation from the Asset Manager, at least there's a confirmation dialog in the customer screen, even if the dialog is defaulted to YES (not recommended)!
We have been reviewing deletes throughout the app. We don’t have plans to add a cart function for invoices and estimates at the moment, though as we haven’t heard this affecting many users.