We have developed a custom workflow system in PHP for our company (academic text editing and related work). Back then (I was not directly involved from the star

We have developed a custom workflow system in PHP for our company (academic text editing and related work). Back then (I was not directly involved from the start) none of the out of the box solutions fit our criteria, and it made more sense to just build a bespoke, custom fitted system. Workflows range from a few days to a month+, with no technical upper limit enforced, as far as I know. We also don't need a huge throughput, so having something super-optimized was not a large concern.