Should i create a Core library for all business applications ? or each one individual?

I was find many companies which creating entities and models for each business applications

So all these apps not reusable.

Now, some clients of the company for example. needs 3 kind of software.

For example [ HR management, Inventory, and Asset management ]

Here's a problems i found.

1. if i created each project from scratch it will take many time.
2. each project can't be reusable. so i can't create asset from Inventory project.

So I need to know following :

1. Should i create a Single Core library which contains Data-Entry controls and so that i can import it in each project ?
2. A Single Core will make me don't create any new data-entry or addons controls. so i just drag & drop and create a Business App that i need directly. without creating a Models for it. Assuming i Use a Custom Control which have dynamic properties that take ( TableID, FieldID's from currently working Form or screen )

Please, i don't ask because i don't know exactly what done. but i need to hear from People who works in Mid-Scale Business Apps or Large Scale one.

In breifly. Guess that your client asking to make 7 Business Apps. that is separately .

Ex : Financial System, Inventory, HR Management, and so ? now all of them is Data-Entry screens and reports.

What exactly will you thinking or do? to gain more time. and reusable components?