In skyblock bonemeal should take 2% time off crops(wheat, stems, thr items that grow off stems, etc.) and 1% time off trees. For example if a crop takes 100 minutes to grow then it should take 50 bonemeal to grow it. Or if a tree takes 100 minutes then it should take 100 bonemeal to grow it. To add onto this, if a crop or tree is halfway done growing then it should only take half the amount of bonemeal to finish growing it.