Assuming we are talking about paste here, I’ve had all sorts of trouble with blocking nozzles too. The good news is, with a spotlessly clean nozzle the printer is amazing. My approach is that after a days use of nozzles, I try to carefully clear out as much paste as possible with a toothpick or similar. Then I put them in an ultrasonic bath filled with flux cleaner and deionised water. I run the bath till the nozzles are clean and then store them. Sometime I stick a syringe in the nozzle and suck the solvent in through it (probably not a good idea to try to push blockages out).
It’s a shame it’s so much effort, a self cleaning nozzle (or paste that didn’t harden so much in the nozzle) would be awesome.