PD Budgeting: Alteration & Prep Time Line Items?

Hey everyone, I'm Sofia, a location scout, and I'm currently working on a passion project, a short film with a tight budget. I've been doing a lot of research into efficient production design budgeting, and one of the recurring themes is that underestimating alteration and prep time is a huge pitfall. This makes total sense to me, having seen things get rushed and messy on set because of it.

My question is, what specific line items do experienced Production Designers include in their budgets to accurately account for this 'hidden' labor? I'm talking beyond just the prop master's daily rate. Are there specific entries for 'prop modifications,' 'set dressing adjustments,' 'build out prep,' or something similar? I'm trying to be as thorough as possible to avoid any nasty surprises down the line. Any wisdom you can share would be incredibly helpful!