The answer, as with so much chemistry, is it depends. What substrate are you hydrolysing, is it a primary, secondary or tertiary amide? What else is in the molecule that you want to preserve?
Both acid and base hydrolysis require concentrated conditions and elevated temperature. There is a lab procedure here that uses sodium hydroxide in water at reflux to hydrolyse benzamide to benzoic acid. The standard cleavage of an acetamide protecting group to give amine plus acetic acid is overnight reflux in 2N HCl or KOH in MeOH at reflux ref here, for a benzamide protecting group it is 48h in 6N HCl or HBr in Acetic Acid at rt.
In my own experience a particularly resistant acetamide required 3 equivalents of KOH in refluxing ethylene glycol to hydrolyse.