About 1/2 - 2/3 of my tenants seem to be renewing lately.
When I do have turnover my goal is to have zero vacancy. I start marketing the property about 45 days out and reduce the price every 5-7 days if needed. Much less expensive to reduce the rent than have a vacant month. Longest I've ever gone with a vacancy is 1 month. I would expect that this calendar year that across my 11 properties I will have 15 total days vacant at 1 of them even though I budget for 3%.
This is similar to what I do. I also budget for about 3% vacancy and have never had a year where I've (even close) reached that budget across all properties. And rarely even go over that percentage on even one property during turnover years.
I put up ads and start processing applications as soon as I know the place will be vacant, which is usually only 30 days out. I do also set the rent optimistically and then bring it down if there is little interest. 14 days is the longest vacancy I've endured and that was with a massive cleanup effort after a tenant trashed the place.
On the other hand I have a place rented now for $575 that (I think could be) renting for $625 or more. Over an 10 day period, I started out asking $625, reduced to 600, then to 575. Looking back, I probably should have kept it at $600 for a while longer, maybe even $625. Yes, the loss of income and footing the utility bills can be costly during vacancy. But it's hard not to think about the $50/mo left on the table. I still tend to lean towards lowering the rent to lease it a little quicker. I don't like raising rents on good tenants, but in cases like this, I usually will make a small adjustment after the second year.