I've had a sort of system that worked to a point during toddler years. I think the baby and toddler years and having multiple little ones is very hard though especially if they are lively and creative.
You're doing a brilliant job. My Mum's best advice is "put your feet up and shut your eyes" and I think there is something to be said for that.
Otherwise, here is my system:
I handed over everything possible to robots. That cost a bit, but no more than a cleaner over a period of time. Here are the robots:
Roomba vaccum cleaner upstairs
roomba vaccum cleaner downstairs
Bravva for hard floors
My toddler really liked the robots so would get really into picking up toys on the condition that he was then allowed to turn on the roomba and then chase it around while it vacuumed. The deal was "lets tidy up so we can run the roomba" and that worked well.
I also bought a lot of plastic boxes and had our attic floored, and a sturdy wooden loft ladder put in that a toddler can climb. We would then grab loads of clutter and throw it in the boxes and then take them up to the attic while the roomba cleaned, and then the toddler would choose a new box to bring back down. That saved a lot on new toys, as attic toys were new enough to be exciting all over again.
We turned our dining room into a utility room, and put a tumble dryer and extra fridge freezer there. That cut down on laundry work a lot and meant that I didn't work nearly so hard managing inventory in a tiny fridge freezer.
Our oven is a self-cleaning one, which again costs money, but no more than a cleaner over time. It saves a lot of work.
Getting rid of nasty old carpets was transformative for us. Our house had been rented before for years and one of the carpets seemed to be generating dust at an alarming rate, which turned the air into an unhealthy fog every day. Once we changed to wood floors I had about 30 minutes less work a day.
I think that more cupboards would help. We have no cupboards and that is the bane of my life tbh. Having somewhere to put stuff really helps as it's impossible to clean until all the clutter is off the floors and surfaces. Getting clutter under control is massively important in order to get stuff clean. I have totally not got that sorted yet.
Another thing that helped me was imagining that I have a cleaner and doing all the stuff for myself that I would have to do for her.
So that means mainly working out what cleaning materials would be needed in each room and putting them there ready to be used and then making a list of tasks that can then be scheduled.
It means, for example, that when I get a second I can just grab a sponge and soap that is already in the bathroom and quickly clean round, rather than having to go down to the kitchen and rummage around and remember that there is no appropriate cleaning stuff, and make a mental note to buy it and so on.
I have the right cleaning stuff in the kitchen always too, and buying too much is okay as it keeps. I also have a spray bottle of vinegar in the kitchen and bathroom. I use ordinary fairy liquid to clean the kitchen and johnson's baby shampoo in the bathroom as they are there anyway and are non-toxic.
I also fine tuned all my cleaning so that it was super-quick and organised a rote of one room per day of the week. Here's what I do:
Kitchen - clear all toys to living room. Do dishwasher. Move remaining stuff all to one side. Clean over with sponge and fairy liquid. Dry with tea towels. Move stuff back and clean other side. Braava does floor. Having a massive stack of tea towels really helps. I put wet tea towels flat on the top of the hob to soften gunk and then it just cleans off with a wipe of the wet tea towel, which saves a lot of harsh chemicals being used. The kitchen is much harder with a crawling baby, and I have no idea what the answer is to that. The crawling and weaning years were very hard for us, what with constantly cleaning blueberry puree off the walls and everything else three times a day.
Bathroom - I spray the sink with vinegar and leave it for two hours. I then clean round with johnson's baby shampoo and the place is easily made spotless because the vinegar has done all the work. I keep kitchen towel in the bathroom as drying stuff is most of the work where there is chrome. Much more than cleaning it. I just wipe the floor at the edges and then all the dust sort of rolls up into balls and the roomba collects them.
Hall, living room and dining room are clutter-controlled one day each per week, even if total armageddon breaks out in between. It means that no matter which day a person comes, there is always one room that is civilised for them to be in.
Bedrooms - the whole family helps to strip the beds and to make them up at the end of the day. We pick up all books and toys and run the roomba. The washing machine and tumble dryer do most of the other work.
Recently I've discovered that one good way to keep on top of the folding of clothes is to do while ds gets into his school uniform in the morning, as it keeps me still while he is concentrating, and gets stuff done.
I also use folding clothes as a meditation activity in the evening when I am so stressed that I have indigestion. It is weirdly effective.
Anyway, this is what I've worked out. It's still hard to keep on top of it all and I only have one 7 year old and no job. With multiple young kids it must be really hard.
Take it easy on yourself. You're doing a great job.
Thanks for letting me list all this too. I worked so hard to figure it all out and it makes me proud to be able to write it all down.