The problem in Spurgeon’s day may well have been over-long sermons. Spurgeon argues for 40-45 minutes as an optimal time frame for a message:
If you should ask me how you may shorten your sermons, I should say, study them better. Spend more time in the study that you may spend less in the pulpit. We are generally longest when we have least to say. A man with a great deal of well-prepared matter will probably not exceed forty minutes; when he has less to say he will go on for fifty minutes, and when he has absolutely nothing he will need an hour to say it in. Attend to these minor things and they will help to retain attention ( p. 134).