Wood glue is also much more flexible than screws and can actually move slightly without preventing the wood from holding together. Screws, on the other hand, are very unforgiving if they aren’t installed perfectly or if you don’t pre-drill holes for them. Glue is stronger under tension because it stretches, so a joint held together with too few screws will eventually come apart at the weakest points. On the other hand, glue joints that are over-screwed in an attempt to make them stronger can crack when subjected to stress.