Here's a question: Would you spend upwards of $300,000 in attorneys fees trying to get your spouse from collecting what he or she is probably going to get anyway? Does the answer change when the dollars change? Does the answer change if the person is in a tax bracket close to 50%, and has to earn close to $600,000 to pay those fees.
Let's say, hypothetically, there is a very long term marriage. The high earner makes about $1,000,000 per year. The low earner wants support to maintain the marital standard of living. In this hypothetical, the low earner worked throughout the marraige and still works, full time, earning about $80,000 per year. Hypothetically, the temporary support ends up being around $30,000 per month. In gross terms, that leaves the high earner with about $640,000 a year, and the spouse about $440,000 per year. Sounds like a lot of money, doesn't it, but hardly unfair to the high earner after 30 years of marriage.
Temporary support in my county, San Diego, is almost always computer and formula driven: Pretty predictable once you agree on the amount for the parties' earnings and tax deductions. Our computer programs calculate net incomes and divides them on about a 60-40 ratio, although it is adjusted for the recipient-spouse's earnings and often ends up closer to 55-45 if the low earner makes a good living.
Long term support [also called permanent or judgment support] is what a judge would order after trial and the division of assets - the court must then consider a bunch of factors, and is not permitted to use guidelines. Notwithstanding that rule, long term support tends to be close to temporary support for long term marriages: Those twenty plus years, especially if a career was built during the marriage.
Knowing all of that, why would anyone spend that kind of money avoiding the inevitable? I don't have an answer, but it's a question that I ask a lot. Especially after watching it happen time and time again. Personally, I'd rather give the money to my ex-spouse than to the lawyers. The lawyer isn't going to walk my daughter down the aisle or come to my son's graduation, and at least I'm keeping the money in the family.