Image Resizing - 72 ppi to 300 with a batch of files?

Thanks to everyone for their feedback. I took a photoshop class and this particular instructor really liked the idea of changing the ppi to the highest you could go to to achieve the print size you desire to hand over to a lab.

To date, I have handed my clients the full JPG files for print and reduced JPG files for email, FB, etc. I realize as my hobby starts to make money, prints might become a bigger part of my future and a differentiator compared to clients printing photos at Walmart or Coscto.

I have a better understanding thanks to all the feedback, although there is still some lingering thoughts???