Correct. The mitigation factor for lacking precision is fuel. It really is that simple. The really hard parts are all done prior to people entering the capsule. Hell, what people don't get is that manual navigation to and from the moon isn't difficult. It's simply a difference of fuel use. The same tools which can be used to navigate to the moon and back have been used to navigate the seas for thousands of years. But computers allow for less resources (fuel, air, food, electricity) and safer trips. Regardless, manual navigation is part of their tools and training.