If it's just me on work travel.... A hour is plenty and 30-45 is fine.... Especially at airports I M familiar with.
If I'm traveling with a group ...my family or a work group when we need to share cars or other arrangements, then yeah I'm a 1.5 to 2 hours kind of person! The chances something goes wrong goes up soooo much when there are more people. Also, if it's older people, then even important to have the 1.5 to 2 hours!!