(mainly asphalt)The property is (dare I say) pristine.

Some other costs were like exterior building paint, asphalt etc. which we could have skipped but exterior is what prospective tenants see first, so it become essential to take care of it to bump up the rents...

The short answer Brian is "yes, but, results may vary", and one BIG variable your not accounting for is that NO real estate has absolute static numbers; there is vacancy to consider, general maintenance but most importantly to never ever forget when doing longer term projections is Deferred Maintenance, those things that DO wear out over time such as roofs, exterior paint/ siding, maybe asphalt, these are some big expenses that if not accounted for can really hit hard. 

I reached out to a local roofing contractor (Supreme Remodeling Inc.) and got a quote that was $15-25K for Asphalt Shingle and $25K and up for Tile for a 1,450 sq.ft SFH.

You want it stripped; don't let them go asphalt on asphalt.

You may not always want that job and need to plan accordingly.15% is a common budget for maintenance.CAPEX budget can vary depending on the age of the systems inside and outside the buidling (does it have a parking lot, is the roof rubber membrane or asphalt shingle, do you have a boiler system or furnace, etc., etc.).Hope that helps - I'm sure there are others I didn't mention.

When managed well, industry experts estimate that you should be able to generate a 30% Return on Investment when you have a 90% occupancy rate at your storage facility.No Toilets – Just steel walls and roof, gravel or asphalt driveways, and a steel door.

Typical asphalt shingles...

A "new roof" is great and will last 20+ years but there are plenty of people that just take shortcuts and put a new layer of asphalt shingles on top of the old ones to save time and money. 

Once the lot is plowed, it will typically be more slick than before it was plowed, due to the thin layer of snow/ice left on the asphalt.