Software engineers get questions of “how much testing is enough” on a regular basis. Existing approaches in software testing management employ experience-, risk-, or value-based analysis to prioritize and manage testing processes. However, very few is applicable to the emerging crowdtesting paradigm to cope with extremely limited information and control over unknown, online crowdworkers. In practice, deciding when to close a crowdtesting task is largely done by experience-based guesswork and frequently results in ineffective crowdtesting. More specifically, it is found that an average of 32% testing cost was wasteful spending in current crowdtesting practice. This article intends to address this challenge by introducing automated decision support for monitoring and determining appropriate time to close crowdtesting tasks. To that end, it first investigates the necessity and feasibility of close prediction of crowdtesting tasks based on an industrial dataset. Next, it proposes a close prediction approach named iSENSE2.0, which applies incremental sampling technique to process crowdtesting reports arriving in chronological order and organizes them into fixed-sized groups as dynamic inputs. Then, a duplicate tagger analyzes the duplicate status of received crowd reports, and a CRC-based (Capture-ReCapture) close estimator generates the close decision based on the dynamic bug arrival status. In addition, a coverage-based sanity checker is designed to reinforce the stability and performance of close prediction. Finally, the evaluation of iSENSE2.0 is conducted on 56,920 reports of 306 crowdtesting tasks from one of the largest crowdtesting platforms. The results show that a median of 100% bugs can be detected with 30% saved cost. The performance of iSENSE2.0 does not demonstrate significant difference with the state-of-the-art approach iSENSE , while the later one relies on the duplicate tag, which is generally considered as time-consuming and tedious to obtain.