You may have to add them back later. In fact, if you do not end up adding back at least 10% of them, then you didn't delete enough.

Often we do things simply because we've always done them. Or because we think we need to. Or because it's our job, and therefore it must be important.

This should come after step two. A common mistake is to simplify and optimize a part or a process that should not exist.

Make sure you don't automate or optimize a process that doesn't need to exist in the first place. Sure, you can make percentage gains by making something better... but why not save 100 percent of the time, effort, or cost involved by eliminating something that creates no value?

Every process can be speeded up. But only do this after you have followed the first three steps.

"In the Tesla factory, I mistakenly spent a lot of time accelerating processes that I Iater realised should have been deleted."

In simple terms, the two major ways to increase productivity are :

• to speed up the rate of production (think increasing the miles per hour) 
• to speed up the time it takes to switch from producing one widget to another.) 

That comes last.

The big mistake in Nevada and at Fremont (Tesla factories) was that I began by trying to automate every step.

We should have waited until all the requirements had been questioned, parts and processes deleted, and the bugs were shaken out.

• All technical managers must have hands-on experience. For ex, software managers must spend at least 20% of their time coding. You don't need general who don't know how to use a sword. 
• Camradery is dangerous. It makes it hard for people to challenge each other's work.
• It's OK to be wrong. Just don't be confident & wrong.
• Never ask your troops to do something you're not willing to do

• Whenever there are problems to solve, don't just meet with your managers. Do a skip level, where you meet with the level right below your managers.
• When hiring, look for people with the right attitude. Skills can be taught. Attitude changes require a brain transplant
• A maniacal sense of urgency is our operating principle.
• The only rules are the ones dictated by the laws of physics. Everything else is a recommendation.