Should I use sales orders on all transactions?

Should I use sales orders on all transactions?

Right now on Zoho Books/Inventory there are 2 ways of tracking inventory. Countability Existences and Physical Existences.

If I want to track them both in the most accurate way, how should I do it. Should I create Sales order for all transactions. 

For example; I have got a POS, If a customer wants to directly purchase 3 items, and he is certain he will buy them, there is no need to create an estimate.Neither a Sales order. With just an invoice it may be enough, but with a Sales order I can track the inventory more accurately. Should I use the sales order in every occasion, despite the type of purchase it is?

The bad thing about using the sales order method is it requieres several more steps and sends notifications to clients that products have been sent.

I would appreciate any insights about it.