As with any stretching question its relative to the persons assessments as to how much, what type, and when they stretch.
As was stated by Steve Oswald if you are training to increase performance, static stretching before a workout can reduce work capacity and strength. But if you have a beginner who has only sat at a desk and computer his/her whole life then the majority of the whole program should be corrective stretching with some strengthening of motor pathways in between.
How flexible are you? Whats your mobilty like? Do you have any compensation patterns? If you don’t have any issues and mobility is not a problem then a basic Acitve Isolated Stretching or Dynamic Warm up prior to for around 10 min and some static stretching and mobility work done after for 10 min is adequate. Remember that this is relative though, so if you have anything that needs extra work then take extra time. Don’t skip it though, you should give yourself at least 5 min if you are in a rush to move through some dynamic warm ups and static cool downs.