Just had the OEM cv boots replaced on my '95 ZJ; they lasted 8 years. Got ones from NAPA put on, & they darn well last more than a few months! Yours should definitely last longer. Where are you getting them? You may want to try OEM boots next time. If mine wear out soon that's what I will be doing.
One reason they wear out (IMO) is they flex a lot, and with a ZJ's very tight turning radius, they flex A LOT! BTW, this is also why I don't think you could or should try to use u-joints instead. The angle is simply too great to allow their use.
1995 5.2 ZJ Sold... but still in the family