I do have reamers but I generally don't find step drills an issue in being over or under sized for holes. They go up in 1mm steps, so if a hole is drilled oversized that's only 0.5mm gap around the circumference. (The larger the diameter, the less significant 0.5mm is). Incidentally, step drills are also available in Imperial sizes. A set of three HSS titanium coated step drills from Toolstation will cover from 1/8" to 3/4". (1/8" - 1/2", 3/16" - 1/2", 1/4" - 3/4"), in 1/32" steps, so each step is 0.79mm larger than the one below it. Three for £16.98:
https://www.toolstation.com/hss-tita...ill-set/p30591
Step drills are a joy to use - they don't judder or snatch, and are essential for plastics such as thin acrylic sheet. They have their limitations - they can only be used for thin material up to maybe 5mm thick, (such as a die-cast alloy project box), but that covers much of what we do. In thicker material such as steel plate, normal fluted engineering drills are needed, but for larger holes they need to be run at slower speeds or they'll judder, snatch and won't cut cleanly. Always best to use a chunky drill vice bolted to the table of a pillar drill when possible, to firmly anchor the workpiece and avoid injury. EG:
https://www.axminstertools.com/axmin...CABEgLKqvD_BwE