Taking into account the average amount of radients per Dreams and Nightmares run, how many runs would it take to fully heat a 5 star item?
Quick Question
At medium forging chances, you require 420 Radiants on average. So that would be 20 runs on average. Sometimes more, sometimes fewer.
At high forging chances, you require 453 Radiants always. So that would be 22 runs.
Keep in mind that there is a lot of uncertainty in the estimated average of 21.75 Radiants per run.
Keep in mind that you can skip almost every fight on the first two levels, and all but the last fight on the last level.
When I took data on Dreams and Nightmares I came out at around 23 rads per run, but there's a HUGE amount of variance- It's not uncommon to get 12 rads or to get 33 rads.
If you do 453 so as not to waste large amounts of progress randomly you end up with about 20 runs.
There is a mandatory 4 minute loading/dialogue perusing per run, and it's possible to beat the level part, i.e. the fighting/running/gameplay bits in 7-11 minutes if you're good, though I have less data on those numbers and only use them for personal reasons. If you're not good it takes about half an hour to run through the levels, assuming that your party overall is good enough to make it through via probably someone carrying.
This comes out to about 4 hours of farming in a serious party i.e. everyone knows what they are doing etc. and 10 hours with randoms/carries, i.e. most players that you see walking around.
To put this in perspective, FSC gives about 18 rads according to Lancer Knightz, but FSC also takes much longer to get through unless you have invites to D27.
http://wiki.spiralknights.com/Lancer_Knightz_%28Guild%29/Mission_Rarities
if you always use x3, which you should unless you like gambling (and possibly losing big), that is 21 runs on average.
from my own testing, you can get 1-2 rads per minute. so you need 4-8 hours of DaN farming per item.