Absolutely.... I just did the math on what I still needed to replace. So for me, I replaced the roof immediately upon purchase so here's what mine simple analysis looked like.
**Divide # years down to a per month cost.
Roof - 25 years - ~$9,000 - monthly cost $30
HWT(2) - Replace both with 3 years most likely - $2,500 - monthly cost $70
Electrical - Replacing both panels in year 2- (now already completed) $2,000 - $165 / month in first year
Furnaces/AC - replacing all within 5 years - (one replaced now) - $5,500 ~$90 / month
So this is certainly not an exact science but this was how I originally looked at it (after purchase) ... not sure if I would have bought it had I thought all the way through it but it got me into the game and has worked out great for me. Just haven't made much money on this one yet.
So to sum it up, I budgeted $325 a month to replace the items that I needed to over the first 5 years.. I subtracted the roof out and added that $30 to my overall reserves since my plan is not to hold it more than 5 years for this property. So basically my $325 a month that I needed to just handle these specific items really cut into my "cashflow" that I originally thought I had. I had a cashflow of about $450 after all other expenses, vacancy, etc. So I actually only have a cashflow of something like $125 on my duplex since I know I'll need $325 a month out of that to do these major repairs. I did completely renovate the rest of the units, kitchen, baths, floors, etc so I don't expect to have major expenses aside from the ones I mentioned.