Why are the remaining times sometimes not present or wildly wrong?
The remaining time to completion of the transaction is calculated using an average time of the time between percentage updates points, extrapolated to 100%. This means that backends that give accurate and frequent percentage-changed signals will get accurate times. If a backend updates the percentage using very course updates (e.g. 20%, 40%, 60%, 80%, 100%) then the remaining time algorithm will not perform well. Similarly, if the duration of 0% to 50% takes 2 minutes and 50% to 100% takes 10 minutes then at first the time will be reported under the true time to completion. It is up to the backends to map the transaction progress to fine-granularity accurate percentage updates, at least as best as possible.
