Hello Niko,
The dried leaf edges are definitely not normal if they have continually been growing in that location. Thats a sure sign that it has/had root rot. Does it keep drying the margins of its leafs or has it stopped?
Do not move them to shade(that will keep them wetter which you dont want now),just stop watering them for 5 days(and then you could probably move them for 2 days in the shade if they dont look too much in need for water. Its ok if they lose the lower 1-2 leafs in the whole process) since the last time you watered and water lightly the next time you water them with another dry spell of 5 days. Then you could resume normal watering every 4-5 days and hopefully they will be ok.Once the rot stops(you can assume it has stopped if the leaf drying doesnt continue to the newer leafs),they need to grown new roots before they will be able to spread their leafs more,so a few weeks are needed anyway to see good progress. Later,once the rot danger passes and the plants start keeping their leafs flatter when not in the sun for a few hours,you can check for other signs such as if a lower leafs bends down prematurely or if the leafs droop more than normal when not in the sun,to see about when you need to water and find a better watering schedule for yourself,as everyone's conditions are different.
A new leaf every 10 days is a little too slow for our hot weather. A new leaf every 5-7days is more like our weather now,especially in small plants which as a rule,grow new leafs faster than bigger ones. If its growing though,it should pull through ok.
Check the soil and see where you find moist soil. I usually wait for the soil seen through the drainage holes to become dryish which leaves about 1/3 of the root ball with lightly moist soil and the bananas still keep growing fast!
If the sun they are getting is mostly morning with a little noon sun,then they probably can go for a week without water easily,without problems.
Btw,the small flies are probably fungus gnats. They lay their eggs usually in continually moist soil. Their larvae increase the rate of decomposition of the soil further increasing the drainage problem and keeping the soil wet for longer. They are an indication of overwatering most of the times,especially if you have them in outdoor pots. They usually prefer enclosed areas that stay humid and are not much affected by wind. Indoor plants get them mostly. As you stop keeping the soil continually moist,they will not prefer these pots as breeding ground as much as they did and you will see less of them.
You could remove one of the bananas from its pot and check on the condition of the soil at the bottom. If its muck,very fine particle and stick to the hands a lot,even a little smelly,then remove the existing soil carefully and repot with new,fast draining soil. If its still ok and has good texture,just place the plant back in its pot without disturbing the rootball.