Experience and novelty can have a hard time getting along in the same person. This is not a criticism. When we start out, we may have many novel ideas but we often lack the experience to discern whether they have potential to make an impact or not.
On the other hand, experience may help us develop that instinct, but at some point we start fulfilling a pattern which deep down, at some level, we know has worked before. This doesn't mean more experienced people get less creative over time (even if in many cases I believe that's what happens), it means they tend to develop a style. Some ideas simply have some people's trademark signature. Again, this is not a criticism. Many times it's quite the compliment.
Experience also tends to plant certain vices, which any industry has. The marketing and advertising industry is not an exception... better yet, it's quite the stereotype of how those vices show up in the first place. Deep down, we're subconsciously affected by what happens around us, whether it's people complaining about clients, the way debriefs are managed, or the tone of water cooler conversations.
Direct contact with our environment can then lead us to get more experience, but also influence our work and posture according to our (new) vices. This is a tricky situation because vices make us stop questioning things which simply are the way things work, that is until someone with zero experience comes in, asks around a couple of basic right questions and we're simply left unarmed.
Recently, while visiting London's Natural History Museum I read a description about our relationship with the sun that shed some light (no pun intended) about this. It helps illustrate a delicate balance we should constantly seek out, and it goes like this:
Sunlight is essential for life. But direct exposure to the sun’s radiation would cause death. The Earth’s atmosphere both shields the biosphere from the sun’s harmful rays and allows some sunlight through for living things to use.
Experience is sunlight. It can be great for us to know the industry from inside out, develop our own abilities and learn. But at some point we have to master our own atmosphere, in order to reap the benefits of exposure without getting burned.