What business management theories work well in your business?

If you've heard of lean management, continuous improvement, or the theory of constraints, you'll know its a way of doing business where you address the weakest link to improve overall efficiency.

Normally I've heard of these theories for improving employee performance (can usually a weak link in businesses), but this interview with Find Accounting Software and RKL eSolutions seems to suggest you can utilize these theories towards a software selection process or anything that might be "bottle-necking" your workflow.

Anyone in a management position here want to share their views on continuous improvement or any theories they may use for their accounting process? Ways to locate and address these weak links?