It’s all depend what you use your MacBook for... or what your work is.... Journalist, (a Toughbook would/could be there be more suitable) - Student, “Starbucks surfer”, “Poser” - generally the RAM utilisation is about for Word Processing (e.g., Microsoft Word, Pages) from 200 MB to 500 MB - More complex documents with many images or extensive formatting may increase usage up to 1 GB.
Safari web surfing can range from 400 MB to several GBs depending on the number of tabs open and the content of those tabs. For example, 5-10 tabs might use around 500 MB to 1.5 GB, while more intensive sites (like those with heavy media) will require more. Depend of settings, refresh etc etc...
Most RAM is used for Video or Photo Editing (e.g., Final Cut Pro, Adobe Premiere, Photoshop) Basic edits on smaller files may require closer to 4 GB, but working with high-resolution images or videos can push RAM usage to 16 GB or more... but than again, really heavy editing work or “professional “ use, you wouldn’t do on a MacBook? You could, but only in emergencies when a Desktop is not available... Or?