With my second birth, I was in hospital for 4 days with on/off contractions, they only did not send me home because I live an hour from the hospital! I was examined on day 1 and was 1 cm only. On day 4 at about 9pm I was having painful contractions every 5 mins and wanted pain relief, m/w examined me, I was only 1 cm still, and told "you are no more in labour than you were 4 days ago, you could go home tomorrow, but definitely no pain relief for you now, back to the antenatal ward".
11pm - I needed pain relief definitely, so went back to nurses, "you were only examined 2 hours ago, there is no way you are in labour", but I will put you on the CTG for 20 mins to look at the contractions for you"
30mins later, I was getting really worried, I was in a side room with the machine strapped to me, and as I had laid there, the contractions had gone from 4 mins, to 3 mins to 2 mins apart and were getting to the point where the tens machine was not doing a thing to help.
M/W walks back in casually looks at the trace, "you are contracting, but you are not in labour". I complained that I really really did need pain relief and NOW, so she causally said, "so do you want me to examine you then?" I agreed and she checked, I was 3cm so was permitted to go to the labour ward. Walking the short distance was not fun, phoned dh to get to hospital.
When I got to the labour ward crying in pain, and I apologised to the m/w saying I needed pain relief right now (same m/w who had examined me 2 hours previously) the m/w apologised and said, "sorry it is routine to examine you on arrival at the labour ward, I know you have only just had it, but I have to do it again". - I was 5cm !!
M/w requested epidural for me, but by the time the anaethesist arrived 20 mins later, I knew things were progressing fast, so asked to be examined again - I was 8cm.
I spent the next 40 mins (making noise) while trying not to give birth before my dh arrived, he arrived just as the head was crowning. (from 3cm to delivery in an hour, from "not in labour" 1cm to delivery in 2.5 hours)
This had me worried for my 3rd labour. But this was slightly different, I spent the first half hour in denial, and not realising I was in labour, on MN chatting, using a contraction timer as the "trapped nerve pain" seemed to be coming and going, then saw the contractions were 5 mins apart lasting a min, suddenly went "oh no, I am in labour". Baby arrive less than an hour later, at home as could not get into car. I only made noise when I was in transition, saying "I can't do this", because I had no pain relief available. But whole labour was 1.5 hour from first twinge to delivery, so fast and furious and over quickly.