The paper presents the results of a sensitive L-band survey of intermediate-age (2.5 – 30 Myr) clusters NGC 2264, NGC 2362, and NGC 1960, using $JHKL$ colors to determine the fraction of stars with circumstellar disks. The disk fractions for these clusters are found to be 52% ± 10%, 12% ± 4%, and 3% ± 3%, respectively. Combined with previous $JHKL$ surveys of younger clusters, the study provides the first systematic and homogeneous survey of circumstellar disks in a sample of young clusters spanning a wide age range (0.3 – 30 Myr) and containing a statistically significant number of stars with masses spanning nearly the entire stellar mass spectrum. The analysis shows that the initial disk fraction is very high (≥ 80%) and decreases rapidly with cluster age, with half of the stars losing their disks within 3 Myr. The overall disk lifetime is estimated to be around 6 Myr, which sets a meaningful constraint for the planet-building timescale in stellar clusters. The implications of these findings for current theories of planet formation are briefly discussed.The paper presents the results of a sensitive L-band survey of intermediate-age (2.5 – 30 Myr) clusters NGC 2264, NGC 2362, and NGC 1960, using $JHKL$ colors to determine the fraction of stars with circumstellar disks. The disk fractions for these clusters are found to be 52% ± 10%, 12% ± 4%, and 3% ± 3%, respectively. Combined with previous $JHKL$ surveys of younger clusters, the study provides the first systematic and homogeneous survey of circumstellar disks in a sample of young clusters spanning a wide age range (0.3 – 30 Myr) and containing a statistically significant number of stars with masses spanning nearly the entire stellar mass spectrum. The analysis shows that the initial disk fraction is very high (≥ 80%) and decreases rapidly with cluster age, with half of the stars losing their disks within 3 Myr. The overall disk lifetime is estimated to be around 6 Myr, which sets a meaningful constraint for the planet-building timescale in stellar clusters. The implications of these findings for current theories of planet formation are briefly discussed.