Your lead generation strategy should be as dynamic as the people you target. Trends change, behaviors change, opinions change... that's the context where lead generation marketing takes place.
A/B split testing is a strategy to see which ideas and CTAs are performing the best, which offers are converting more effectively, and which copy wins your audience better. It helps making objective decisions in regards to experiments until you find things that work.
In order to not let your lead generation strategy become obsolete, you must keep it up-to-date. If it was good enough for your customers a year ago, it may not be good enough for them today. Find out what your customers want and give it to them.