How easily customizable are SAP industry-specific solutions?

First of all, i've a completely superficial knowledge of SAP. according to my understanding, they offer some of enterprise precise solutions. The concept seems very exciting and i work on something similar for banking enterprise. the largest undertaking we face is a way to adapt our merchandise for distinctive clients. Many principles are quite similar across organisations, but there are always some consumer-particular necessities that should be resolved thru configuration and customization. frequently this calls for reimplementing and developing customer specific capabilities.
 
I ponder how efficient on this sense SAP products are. How a lot attempt needs to be spent with a view to adapt the product so it satisfies precise patron desires? What are the mechanisms used (configuration, programming and so forth)? How could this examine to developing custom solution from scratch? Are they capable of leveraging and promoting best practices?