I was having a discussion the other day about the right number of links to include in an email. The email person wanted "x", the product marketer wanted "y" number of links in the email. Of course, this division of thought led to the whole process slowing down. It also sows the seeds for a big, fat, ugly disagreement.
The real answer is simple - "let's test it!"
For anyone who works in a digital marketing space and does not consistently test their own assumptions, you are doing yourselves AND your customers a huge disservice. Digital marketing is an incredible playground. You can construct an almost infinite number of test and - best of all - MEASURE the results.
There are two big issues with testing. The first is "resources" in that you don't have enough people to set up tests. If this is your reason for not testing, then maybe your tests are aimed way too high. Rather than test simple things that can build your track record of testing success, you try to design the "perfect" test that is way too complicated. Or - despite protestations and executive presentations to the contrary - your organization is not really sold out on digital marketing.
Testing subject lines is easy (and valuable). Testing the number of links is a little more - but not much more - complicated. Testing landing page A vs B can be done simply. Testing multiple variables in a high-speed manner can be easily accomplished via software. It's not hard to get started - all it really takes is will.
The second - and much larger - problem is that once you decide to test, you need to leave your ego at the door. The goal of testing is not to prove what a genius you are - it's to prove what works. If you design a test so that the only correct answer is the one you happened to think of, then you're cheating.
I worked at a company where the CEO "designed" the web site on the back of a piece of paper. No testing, no thought. Just instinct and "genius". To this day, you can't sign up to receive email form the company - it just wasn't part of the CEO's genius...When people wanted to test the impact of letting customers sign up for the site (yes, it's THAT bad), the suggestion was rejected because it didn't fit into the "overall design" of the site. A fine example of ego-based test rejection.
Digital marketing offers a wealth of opportunities to learn about what your customers really want, as well as designs and approached that make them want to buy.
The answers are there - all you have to do is test. Check your ego at the door and quit guessing.