First of all, your branding is more than just your logo. Branding is the perception that people have about your business, for that reason you can recognize some companies even without seeing their name or logo. So taking your company logo and adding it to a random picture or marketing piece is not enough to communicate your company`s message.
You brand identity is a detailed combination of images, typefaces and colors that need to communicate the same IDEA or FEELING. Your message must be consistent and all your marketing communication should be more congruent.
It is always important to bring new and refreshing elements through your marketing, so you can occasionally change some visual elements, but they must remain relevant and related to the product or service you offer. You can change typefaces and shapes sometimes, but you must always reflect your corporate culture and transmit the emotions you want your customer to feel.