Antibiotic pharmacodynamics splits agents into concentration-dependent and time-dependent killers. For concentration-dependent drugs, the higher the peak relative to MIC, the faster and more complete the kill; the key indices are $C_{max}/MIC$ and $AUC/MIC$.
Aminoglycosides are the textbook example. Their bactericidal action improves with rising peak concentration, and they exert a substantial post-antibiotic effect, meaning bacterial regrowth is suppressed even after the drug level falls below the MIC. These two properties together justify extended-interval (once-daily) dosing: a single large dose gives a high bactericidal peak, while the long drug-free trough reduces accumulation-related nephrotoxicity and ototoxicity.
By contrast, $\beta$-lactams, vancomycin and macrolides are time-dependent — killing is maximal once levels exceed roughly $4\times$MIC, so the goal is to keep the concentration above the MIC for as long as possible ($T>MIC$) rather than to chase a high peak.
\[\boxed{\text{Aminoglycosides} = \text{concentration-dependent killing}}\]