It's easier to memorize the Starbucks menu or the NFL rosters.Section 179 basics- can deduct 100% of the cost in the 1st year- applies to 3-yr, 5-yr, 7-yr and 10-yr assets and "qualified improvement property" (a separate post would be needed to explain)- cannot create a net loss- minimum 50% business use required- other limits and restrictions applyBonus depreciation basics, as of today (mid-2023)- 100% of the cost in 2022, 80% in 2023, 60% in 2024, and so on until 0% in 2027- applies to assets with up to 20-yr life- can create a net lossBoth methods have their pros and cons, and choosing between them, as well as generally optimizing depreciation, is a job for an experienced accountant.Cost segregationWhat cost segregation accomplishes is extracting faster-depreciation property (as in 5-yr, 7-yr and 15-yr) out of slow-depreciation real property.

Should I optimize my current property (i.e. rehab it to its full potential) or use that capital to purchase my second investment property?

Does not make sense, I agree.Yes, extremely frustrating, but everyone's tax situation is different, and the only way to optimize your taxes is by working with a competent tax professional. 

Do everything you can to learn and minimize that risk, but remember you don't have an endless amount of time to figure this stuff out and conditions are never going to be optimal.