To all those starting out in Photography or maybe you are on the wrong course, PLEASE shoot in Raw if you are being paid to shoot.  

Be a responsible professional and give your clients the best possible quality by shooting in Raw.  That way the jpeg images they receive from you will only have been exported from a Raw file so it's only being done once.  Give your clients the best!

From the Adobe Website:

"Save your photos in PSD format (instead of JPEG), unless you plan to share your photos or use them in a web page. Each time you save in JPEG format, the image data is compressed, potentially causing some data to be lost. You may start to notice reduced image quality after saving the file as a JPEG 2‑3 times. The disadvantage of saving in PSD format is that the file size increases significantly because the file is not compressed."

Each time you save a jpeg it loses quality, even after only 2 saves.  You should be working with PSD files in Photoshop or Raw in Lightroom to preserve the image quality.  Hope this helps!