I would think its too early to be considering the op on the strength of two blockages (although obviously blockages are very serious and its a scary thing to happen I know
) - its very common for a 2nd blockage to happen almost immediately after a 1st one, and many cats wll never block again after a 1st or 2nd blockage.
I would be looking at diet - wet food only (not necessarily prescription), look at the ingredients - avoid anything with cereals, grains, soya (listed as vegetable proteins, derivatives of vegetable origin, vegetable protein extracts etc) or veggies. These don't have to be expensive diets - for instance Classic Cat Food by Butchers and Whiskas Supermeat do not contain cereals, bit low in meat content, but you could mix and match with the higher meat content, Hi Life real meat pouches, Bozita, Purely from PAH etc.
Struvite crystals form in alkaline urine, so higher meat wet food (or try a balanced raw diet) will ensure the urine is slightly acid without the need for prescription foods - and will prevent crystals from forming. Also stress can cause an alkaline urine, so if stress is a possible cause, perhaps look at Feliway diffusers, and/or Zylkene. You could think about Cystaid/Cystease which helps to sooth the lining of the bladder.
My cat Ben blocked some years ago now, luckily he didn't block again - it was due to a combination of stress and dry diet - but I changed his diet to wet only, then to raw and had no further problems.
As you say, the op doesn't remove the cause, just prevents a dangerous blockage, and it is still early days for the diet to have any effect an any other issues such as stress, to be resolved.
All that said, my friend's cat had this op a long time ago because he continued to block (there wasn't the knowledge about the condition then as there is now) and he was fine afterwards.
