Work out critical path duration instantly with clear inputs, formula shown and shareable results.
The critical path is the longest chain through the network and it sets the project duration. Equally important is the float on near-critical paths: a path with only a few days of float will become critical as soon as it slips, which is where most schedule surprises originate.
Critical path
Project duration = Longest path duration
Total float
Float on a path = Critical path duration - Path duration
Yes, and it is common in well-optimised schedules. Multiple critical paths mean multiple simultaneous sources of delay risk.
Because compressing the critical path simply makes the next longest path critical. Schedule improvement is iterative for exactly this reason.