Sometimes it can take months! I've read where a few people waited near a year to see any breeding! I was lucky, when I got my first batch of cherries, I had babies a couple weeks later! It's been a few months now and I'm just now seeing more baby shrimplets.
Meters such as TDS and pH come with reference solutions or they can be purchased separately. If such meters are used the reference solutions are necessary. These solutions are needed confirm accuracy and to recalibrate.
Times aren't great economically speaking and people are finding ways of cutting cost; keeping thermostats low is certainly one way to achieve this. Not going to say heaters are essential for all or how many this would affect, but those in colder climates such as the Northeast certainly would find need for them unless they keep their house warm 24/7. When I'm feeling generous, my thermostat is set to 60, otherwise, its a cozy 55 room temp all winter long. Not saying everyone is as frugal as me, but I would imagine the money conscious are at least setting thermostats lower for when they aren't at home or going to bed All relative I suppose.