Rewriting my comment as answer:
If we increase the time quantum alloted to each process, the number of times the process will be scheduled will either remain same or it will decrease, it will NEVER increase. However, the turn around time may increase of decrease given the scheduling pattern.
Its easy to see where this will decrease. Case where it will increase:
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Initially time quanta 2
P1 needs 7 time quanta to finish and P2 and P3 needs 10. All arrives at 0
P1(2) P2(2) P3(2), P1(2) P2(2) P3(2), P1(2) P2(2) P3(2), P1(1), P2(2), P3(2), P2(2) P3(2)
TAT for P1= 19, P2 = 25, P3 = 27
Avg TAT = 23.6667
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Increase the time quanta to 3
P1(3) P2(3) P3(3), P1(3) P2(3) P3(3), P1(1) P2(3) P3(3), P2(1), P3(1)
TAT for P1: 19, P2 = 26, P3 = 27
Avg TAT = 24
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