Either I have been very lucky, or there is less infection than people make out. One thing to remember is the water comes from the tap with a kit and is not boiled. So you want alcohol to form quickly to stop other organisms from feasting on your fermentables. The most important thing with kits is the temperature. Get that right and you get a good brew. There is some leeway but where and how measured makes a difference. I found stick on thermometer strips are good, but since they are not insulated from ambient air can be out by a couple of degrees. Same with measuring air temperature inside something like a fridge. So a sensor under something like a sponge will give a more accurate reading.
You don't need the accurate reading, but you do need to allow for inaccurately. So stick on thermometer in kitchen and brew doing fine in early stages at 17.5 deg C, but in a fridge with sensor under a sponge held hard against fermentor side found lower limit 19.5 deg C, however latter will run start to finish. With the stick on at finish it needed to be warmer I needed that 19 deg C to finish.
As to upper limit I found even getting to 26 deg C on stick on the brew was drinkable, but more bitter than when held at 19.5 deg C. The temperature also impacts on time. I am sure if I held the beer warm enough you could get that 7 day time, but at 19.5 deg C I have found around 3 weeks before ready to bottle. Once or twice a brew has stuck, the problem is when the yeast is damaged and stops it signals to new yeast to stop also, so when this happens one has to transfer to clean fermentor and pitch in about double the normal quantity of yeast to get it started again. However sticking is rare. However because it can stick using a hydrometer is always a good idea. The higher the start reading the lower the finish reading so even with hydrometer you can make mistakes.
So cure is use plastic bottles. Using 2 litre plastic pop bottles has a lot of benefits. You can squeeze bottle and find if bottled too early without opening bottle. 40 pints needs around 12 pop bottles so bottling is easier. Also you can replace the cap so one 2 litre bottle can last 3 to 7 days after opening so you can if you want drink less.
When I started I had no hydrometer, no air lock, no temperature strip, and started syphon with mouth the latter I still do. It would sit for at least 4 weeks before bottling and other than ginger beer and larger I have not had a failure. The air lock was first aid, but found leaks even with screw on lid were a problem. Used an electrical stuffing gland sealed with petroleum jelly to stop leaks and it worked well. I knew when bubbles dropped from 6 a minute to 1 every 2 minutes it was finished. But the hydrometer was then bought so although the air lock gave first indication the hydrometer confirmed it. Brewing in kitchen 2 weeks to 8 weeks it varied a lot. Now in fridge with thermostat controlled heater it takes 2 ~ 3 weeks every time. I also no longer need air lock and very rare for hydrometer to read too high.
If fresh pop bottle I just rinse out, if used for beer before I use sanitising fluid, mainly as I forget to rinse as soon as empty, never put away dirty equipment as yeast seems to bake on if you do. I keep in bottle for 3 months to a year before drinking. I stop brewing June, July and August as too hot, which means end of September down to last 80 pints in stock. June likely 300 pints in stock. Beer brewed too warm does improve with time, so tended to keep beer, today with careful temperature control really no need to keep so long.
At first syphon tube was too short. I found because the beer has CO2 in it you need 12 inches between bottom of fermentor and top of item syphoning into or the CO2 causes a bubble of gas causing syphon to fail. Also if you put tube into top of bottle it froths up, you need tube at bottom to fill without froth, so you need a tap. With a tap midway in pipe it is so easy, Turn off transfer to next bottle then turn on again. I use a simple clamp to hold pipe on fermentor, if pipe moves you stir up sediment. Also it may not stay at near bottom.
To reduce sediment I transfer to clean fermentor after around 10 days. It's not required, but does reduce sediment in bottles. If fermentor is not going to be used within a day I put sanitiser in it, but if used straight away for next brew I just wash out. As I said kit beer uses tap water so no point going OTT. Brewers doing Larger from scratch have to be very careful as it takes so long for the alcohol to get to a level to stop infection. You will note kit lager runs same temperature as bitter. Since we do use tap water we can never really blame cleaning for a bad brew we will never know if problem was in water or equipment. But clearly no harm in good cleaning, and I do clean well, but don't use that much sanitizing liquid.
The German government before Lager was invented would not allow additives to be added to beer. This included yeast. So the yeast in the beer came from the stirring stick and every family guarded their stick as this had their yeast on it. Clearly they did not clean the stick very well or there would be no yeast. They also found specially with larger in the summer it was too warm to brew. So the first brew after the summer was a celebration, so that's why we have the beer festival.
Good luck with your brewing, you really have to be unlucky for it to go wrong. Today with a thermostatic controlled fridge I only look at each brew three times. Once at start, once at transfer, and once when I bottle. Takes exactly same time every brew. Hard to remember early days three years ago when I counted to bubbles in the air lock.
