Yes, the process actually does get harder, before it gets better.
Achieving a clean liver is like climbing over Mount Everest; Once you decide to carry out the first flush, you have basically bought yourself a one way ticket over Everest - you can't decide to stop half way up or come back down the way you came, you have to continue and complete the process,
Once the first batch of stones is moved out, the liver is extremely ambitious to move the rest forward to get it out also, so it just keeps pushing forward.
The material at the back of the liver can be bigger, harder and denser than the material at the front, so as it moves forward, the symptoms get worse, until they are expelled.
Andreas mentions several times in his books that even just one batch of stones can block bile flow just as effectively as a liver packed full of congestion, and so the real benefits of having clean bile output channels is not fully realized until the last batch of congestion has been released.
What I can tell you though is that it does get easier as you go in other aspects, like emotional. You will feel lighter and happier as you continue, but your body may just hop along until the very end due to all of the work load it takes to mitigate the effects of poor bile output and blocked waste elimination channels, and to heal the liver after each flush etc.
The process is extremely worth while though - the amount of pain and suffering we have to go through when considering the length of time it takes to develop such a congested liver and how serious the condition is, is minuscule.
From everything I've learned, I am confident that liver congestion is really one of the only diseases that exist. The rest are symptoms of this disease ... and symptoms are the body's own survival responses, carrying out balancing acts to maintain life under these unnatural circumstances. It is just amazing that the body stays alive when it's not digesting and it's waste materials have no where to go - it is the most ingenious mechanism I've ever studied.
Keep flushing and the good work of learning and sharing on here, and you'll find that when you reach a certain stage, all of this was worth while in ten fold ;)