What’s some advice to get good at estimating rehab costs on your flips quickly ?

look into j. Scott's book on estimating rehab costs. It's a great resource for any rehabber, especially if you are newer at it.

experience, no book is going to give u the magic formula, sorry,,,,, your best bet look at a few properties with a contractor get an idea what they are charging for certain things in your market. labor rates are different per trades per area, material costs vary so on

We provide an estimating service for contractors that helps them systematize their estimates. It is simple and effective for the busy, growing companies. It works in every town, so much we are able to provide full detail estimates jobs all over the country! What we do is ask them for their historic costs (previous jobs) of like projects. Input that data into a spreadsheet that averages out the labor rates and material allowances separately. Moving forward we use Bluebeam to quantify the drawings or walk the job with a tape, this then gives us the quantities necessary to have a general idea of what things costs for each GC. You must know the difference between the scopes and understand what drives prices. For you I would be persistent to one of the contractors you think may have organization to their jobs. A good indicator is signage, both on vehicles and jobsite, signage plus a website usually means they have systems they may be willing to share with enough lunches and trade-offs (coffee or drinks). Good luck