According to The New Apex Queueable Interface, from October 2014, we were told that chained Queueable calls would be exponentially delayed up to 64 seconds, chaining Batches would be exponentially delayed up to 240 seconds (four minutes), and suicide scheduling would be restricted to 300 seconds (five minute) minimums. This has a considerable impact on some of our code, which would would make Queueable an attractive option over Batchable (except for, of course, I don’t know if we can chain queueables that callout). Today, in Spring ’15, nothing behaves the way it’s documented there. Are these limitations still coming, or have they been scrapped?
We experienced the penalty delays for chained Queueables in the past (although documentation is rubbish with regards to this). We have 8-10 chained Queueables at times and the
AsyncApexJob entries would show a ~60s delay between Completion and Creation but we have not seen these delays for a while now (I would say at least since 1 year ago).