I have quite a few container plants and most take about an hour (some even more) for the excess water to drain out completely. I raised the issue with my local nursery and they tell me it's fine, no need to worry. The internet however says not more then 15 mins. The pictures below are from the nursery showing how container plants are sold here. It's just topsoil with no amendments other then a little compost. Should i be worried? I hear adding sand helps alot but then again, i also hear that doing so will further compact the soil so, not really sure what to do here.
There are tons of things that can be added to potting mix to add drainage. Pumice, Granite, Gravel, Scoria, Caclined Clay, Calcined Diatomaceous Earth, Perlite, Bark, best to avoid Sedimentary rocks, but some types will work just fine. Anything that is slow to break down will work, even Styrofoam, not that I recommend using, especially not with food crops, but it will work. Some people are able to grow in straight compost. Adding organic matter to your soil will help. even terra cotta pottery broken into piece can add drainage. I am sure you have something you can add.