Not specifically software, but I divide my donations into three categories - for my budget, that’s basically the $10-20 range, the $20-500 range, and $500-2000. I track the donations I make over the year, with a target in mind. For me, the target is 10% of income.
I decide which organizations are doing the most important work, and prioritize those. I try to donate monthly to those that I make use of regularly, then I give the rest as what comes up from day to day.
I consider free software to be a social good, so I don’t separate it from other giving.
True, but most orgs and devs would take the reliable monthly income rather than an unpredictable infusion every two years. If it’s a massive donor base, maybe those things even out. For smaller, active projects, I don’t mind giving a percentage to the bank knowing that they can rely on my donations every month. The larger annual gifts are usually reserved for orgs like clinics, food banks, and community institutions that can handle the fluctuations.