Well mostly. A weed here or there isn't going to hurt you is it? That's the first thing a lawn owner needs to decide. How many weeds are too much? If you can tolerate a few dandelions or a slight intermingling of clover, you may never have to apply weed control methods again.
Keep an eye on them though. Weeds can spread quickly if the conditions are right. Monitoring is a big part of an Integrated Pest Management program. IPM is basically a way to approach pests that is all encompassing rather than reactionary. If you notice the weeds are creeping in and threatening to over take the lawn they may need to be controlled, physically by hand or garden tools, biologically using natural solutions, or as a last resort, chemical herbicide.
The thing about weeds is that they are there for a reason. They are messengers indicating a deeper problem. It could be poorly drained soil, compaction, pH imbalance, excess shade, nutrient deficiencies, too much water or not enough water. Try to identify the underlying issue and the weeds will likely not be a recurring problem.