I didn't realise I wanted downtime rules until I looked at
the ones from A Light In the Dark. Then I immediately realised I did. A few things didn't fit for me though; they're optimised for a living campaign, so they're a bit too detailed in places and a bit too simple in others for my home game.
So I wrote my own, which you can read here. They're very heavily patterned after the A Light In The Dark ones, with a few modifications to suit my own biases.
I've never been completely happy with how I've handled downtime. It felt a little like an underbaked idea, a randomised tax the GM imposes; "well done for finishing that run. It's now going to be... ummm, let's say three weeks until your next one. Pay lifestyle costs. OK next run!" This system puts players in control, with a series of options they can pursue. Hopefully, the balancing works where all the options have their own attractions, without anything being overly powerful or creating a cognitive dissonance around "well, why are these people shadowrunners, then?" It also puts some emphasis on how being a shadowrunner is brutal work - it takes time to heal up, to get 'ware fitted, to train and improve.
I've tried to minimise dice rolling, including a speedy gear acquisition path that makes stuff easier to get hold of when the schedule isn't tight. I've added a sort of resource currency for contacts, to represent the flow of favours back and forth to them, and hopefully give a little flavour of being part of a group of criminals. I've added zero-cost healing and gear repair options to recover between runs, which formalises the handwaving I was doing anyway. And I've added a very light progression system for contacts, both finding new ones and improving loyalty with the ones you have.
I've also taken the chance to buff a few things I feel are a little underpowered in RAW. Sleep regulators become quite potent, for example. Faces should shine here, able to butter up contacts for future favours as well as find new contacts more easily. People with good technical skills might make a non-trivial amount of nuyen on side hustles, maybe even enough to make rent on a crappy apartment - but no more. They're still gonna be hungry.
Feedback welcomed! I'm still very much moving some of the numbers around, and trying to balance options against each other; I expect this will continue as it gets a proper playtest. But please do tell me if you spot any egregious oversights or exploits.