Detergent, fabric softener, start the washing machine
You must always bear in mind the power of habit and inertia.
For example, it’s inevitable that once you’ve added the detergent and fabric softener, you think that the next step is to start the washing machine.
It has only happened to me once in my life, two weeks ago, but it’s natural that if you’ve already put detergent and fabric softener in the machine, you’ll press the wash button without thinking — having forgotten that the clothes weren’t inside the drum yet.
(It’s even natural that you won’t realise this until the machine stops running, when you go to collect the clothes and then you find there are no clothes.)
Perhaps the time the inner tub spends alone, spinning just with water and detergent, is actually a good way for it to clean itself, but in any case, I recommend that the first step when doing laundry be to put the clothes in the washing machine drum.