I was thinking about posting this midround but never really remembered or had the time when i remembered.
how to make production last forever without much effort or cheating:
1) place your order. lets say its 100000 FI class and you use all your light factories. This will take you 10 ticks
2) after 9 ticks you ADD a fr/de or cr/bs class ship to the same production. add 1 ship! with ALL your factories of that type. You can also do this immediately but i prefer doing it as late as possible
3) after you have placed this order, and ALL your factories are being used on that 1 ship, you change the amount of factories being used to 1. This one factory will now be set to do produce all the other factories factorycosts including the 1 ship you ordered. This will add a LOT of ticks to your production (i usually added 18 ticks) every time this new order is finishing ETA1 or whenever you got time to re-add, simply cancel the 1 ship from the order and repeat this procedure.
tip: this means that your main production in theory is always ETA1 out and is deadly for your incs
also as an other tip i would like to notify all players about the factorycosts i just mentioned. if you at night around 2000 gmt or something make all your factories produce just 1 ship in every class you will have factorycost already done when your incs appears (if you get any) and this makes a SIGNIFICANT reduction to how many ships you can produce in time for your incs. usually you can spend your ENTIRE stockpile in time by using this trick
This is only exploiting the possibilities given to us by changes in the manual and is not cheating. all experienced players use this and its only fair that everyone knows about it