This discussion needs no pictures.
Many people renovate very old or simply older homes. In very few discussions and suggestions have I seen recommendations for having the existing painted surfaces tested for lead. There are comments about asbestos removal and lead removal when doing major remodeling, but I do not recall seeing any suggestion or comment for lead testing for wall paint in rooms which will simply be repainted. Most people (homeowners and contractors) will sand the walls before painting. That activity can release lead into the air if the sanding removes more than the most recent coat of paint. Any crack repair will expose several coats of paint. Painting contractors will often use masks, and if they have extra equipment, may even use respirators in older homes.
It is always worth having testing done....and if lead is discovered, it is always worth it to have it professionally stripped, sealed or removed (or whatever is required to make your home safe for your family).