(1) I would trust TurboTax, myself, if the data were entered properly to begin with, and the data were simple. But, at my old law firm I was sternly advised, and I think this is EXCELLENT advice, you cannot let the program do it for you, you have to do it in Excel spreadsheet. And if you ever switch away from Turbotax, or your data gets corrupted somehow, or can't be imported from last year (we've all been there!) then you have a big problem reconstructing the prior years to know what happened re depreciation.
For another thing, Garbage in Garbage out. You might not be able to enter the correct things or enter them correctly. Time and again I found this was a problem. I know I wanted 10-year amortization but program won't let me.
Or Turbotax convinces you to use the wrong MACRS life for your asset.
(2) I agree with Randy that the CPA does NOT have YOUR interest at heart. They have a CYA interest. You should be able to explain and defend what you do and what numbers appear on your returns.
(3) Worrying about separating out the floor (27.5 year property) and the roof (27.5 year property) from the shell (27.5 year property) from the deck (?) to the skirting to the etc etc etc on a used home that you buy for under $40k is a waste of time. It's one thing to do it for a park where the numbers are large and your're in the long term hold (presumably). Most of the park can be depreciated at 15-years, which is very advantageous compared to residential (27.5) or commercial property (39).
The difference between 5-year property and 27.5 year property is you get 20% per year on the first and less than 4% on the latter. But used appliances that are used 5-year property are not going to be very valuable, come on. Most of what you pay for is the "house." And aren't you going to sell this house within a year or two, anyway? You're frontloading some expense but it's relatively small and for a relatively short period of time. A realistic segregation of a $40k home would be maybe $2k for everything other. It just doesn't make sense to worry about this fine-grain separation of assets you buy used for such small numbers.
A new home, well, you actually have the invoice so you can do it right. Put it down for 27.5 years, and a new appliance okay whatever that is (5-year?) and you can break it out per what you actually paid for the appliance, per invoice. This is a little more respectable than fudging the numbers on a used home that came as a unified whole. In this case it's no extra work to do it accurately and you have backup for your allocations.
But worrying about pulling out the non-27.5 year property from the home is going too far for too little benefit, in my opinion. It is also most likely indefensible at audit if you purchased the home as a single item. And most of the property you would segregate (roof, furnace, flooring) is all 27.5 property anyway.
See IRS publication 946.