I have many hives, and rarely spend any more than 10 minutes per hive.
in summer, once a week, make sure they have enough room, check for the queen or eggs.
check the general condition and thats it.
Once you become experienced, it is not even necessary to do this. You will recognise the weather and bee conditions and be comfortable that no action is required.
bees don't like to be messed with and newbies can lose a hive because they mess too much.. less is better.
in winter, many do not check them at all. in autumn, I give them syrup (to replace the honey) and fondant around new years day. Some feed in spring. I only do so if necessary.
treating with thymol in autumn and oxalic on new years day are the only treatments I give. A couple of my hives have had bad cases of varroa (caught swarms), but they do not really suffer too much. I have never had nosema (another common disease), but this can be avoided by adding thymol to the autumn feed and making sure they have fresh water to drink from.
Apart from a single case of chalkbrood (caused by stress from moving), i have not had a disease. the really serious diseases are on the decline.
like keeping pigs, you can spend 10 miutes a day with them or many hours. bees are the same, but the quicker you are in and out of the hive, the better it is for the bees..
beekeepingforum.co.uk is recomended. it does not have the politics or corruption(? ) of the BBKA.