I just went by Susans quote (she's one of the subbies) maths isn't my strongest subject nor Susans. 
this was base on our own job david , thing is with the farm we did it was great , they were set out real nice , the roads were all stone chipped however you could add 4 days easy on this if its boggy , with no roads on it ect ect 45000 is a lot and theres no way I would take a job on this size trying up two vans for say 14/15 days
that two weeks behind in normal work throw in three days of rain and both teams being tried from working flat out you will be 3 weeks behind befoure you know it which will take all the profit out of the farm clean yes it nice to get a lump of cash but its not nice being three weeks behind in work and rushing around like a fool
I think that's what you get if you sub these type of jobs though. Unless you focus on big one off type jobs, what normal regular business running at a good capacity could just absorb this type of job?
yes your right if your only gearing up for these big jobs you will be fine and just move on the next when finshed however this alone causes problems ,
waiting around for next job and earning northing if your not a year pre booked , if you lose a job that could be 8k ayear down the drain not just 12 pounds every 4weeks which is hard to replace
we run to be busy with normal work and try to get the odd big job in as I want my guys out earning from the off , ok theres always alittle wiggle room , by moving jobs to sunday and freeing up the odd few days ect ect
get the lads to work over time but to pull two vans off the road for half a month soild isn't what we want
its down to your market place and wear you want to go in the trade ,