yes, unpredictable - very different from DD1 and 2.
The MWs kept telling me 3rd labours are notoriously unpredictable when I was in labour with my third two weeks ago and all I kept saying to them was 'yes I know, I read that on MN last week - but I didn't believe them'
My third labour was very stop-start and that is very common apparently. For about 3 weeks before he was born I had contractions, proper ones - not BH, which would start up at 11pm, keep going until 5am then stop suddenly. I was knackered by the time DS came along. When it did kick off properly it was very quick - DDs were 32 and 16 hours established but DS was 6 hours max.
DD1 on time, 32 hour labour, back to back, head engaged at 32 weeks
DD2 a week early, 16 hour labour, back to back, head engaged at 32 weeks
DS 10 days late, 6 hour labour, he turned back to back at 37 weeks having been in the perfect position up until then, head engaged during labour.