The surprise is hollow block, common in older and mid-market buildings across the northern emirates and in plenty of Dubai and Sharjah stock from the 1990s and 2000s. The drill punches through the block face into a void, the plug spins uselessly, and an inexperienced installer just moves over ten centimetres and tries again, leaving a trail of holes. The correct answers are longer plugs that grip the far face, umbrella-style cavity fixings, or for heavy mirrors and cabinets, a chemical anchor with a mesh sleeve that mushrooms resin inside the void. This is exactly the kind of judgement you are paying a professional call-out for.
For gallery walls and multi-frame layouts, watch for the laser line. A cross-line laser plus paper templates taped up for approval before drilling turns a two-hour trial-and-error session into forty minutes with zero spare holes. Good finish standard: frames level and aligned to the laser, no cracked plaster around fixing points, and every anchor flush, not proud of the wall.