Which time should the last watch show?

In a time-sequence pattern puzzle, first find the interval between each pair of consecutive terms by direct subtraction; if the intervals alternate between two fixed values, extend the sequence by applying the next interval in the alternation to the last known term.

1. First watch to second watch: 4:32 to 6:35 is an increase of 2 hours 3 minutes.

2. Second watch to third watch: 6:35 to 5:19 is a decrease of 1 hour 16 minutes.

3. Third watch to fourth watch: 5:19 to 7:22 is again an increase of 2 hours 3 minutes, confirming the pattern alternates between +2 hours 3 minutes and -1 hour 16 minutes.

4. Applying the next step in the alternation (a decrease of 1 hour 16 minutes) to the fourth watch's time: 7:22 minus 1 hour is 6:22, and 6:22 minus 16 minutes is 6:06.

Cross-check by applying the full alternating sequence from the first watch: 4:32 + 2 hours 3 minutes = 6:35, 6:35 - 1 hour 16 minutes = 5:19, 5:19 + 2 hours 3 minutes = 7:22, 7:22 - 1 hour 16 minutes = 6:06 - consistent at every step.