Quick am I wrong for Question

[cogswel__cogs]

Am I stupid(Which is always a very high possibility) for often just choosing the columns for my pivot tables data this way I don't need to worry about their size if I add additional data.
Sometimes I will use tables if I have added formulas, but I often just highlight the columns.

 

[RoryA]

I don't know about stupid, but it's not good practice. It will increase the size of the workbook as well as including blanks in all your fields.

 

[cogswel__cogs]

So most of you don't do this.
I will follow, I try to do what the smart people do.
Is it same bad practice policy wit (Sumif/vlookups?)with formulas?