I remove spam when I see it or when it's reported to me. Unless, of course, I am on holiday with other things to do and/or poor Net access, as is the case at the moment. The answer to your question is that obvious spam is removed ASAP, but ASAP may not be quite as early as you might like. No spam messages have remained for longer than a day or two since I resumed moderation of this site.
Try to keep some sense of proportion. Unless you are exceptionally gullible, the spam does no more than offend your sight; and if you are sufficiently gullible to be taken in by what it offers, you are probably beyond assistance, certainly far beyond anything I can do to protect you from the Big, Bad World.
Jeremy