Deterministic-time slicing will help to support longer running operations without resetting the instruction counter: Deterministic Time Slicing
Implementing a heartbeat/timer like functionality based on long-running operations is not feasible for two reasons: 1) the operation runs in the context of the original round, so ic0.time() will return the same value (we cannot change that) 2) the operation uses CPU cycles while it is running so it is going to be much more expensive compared to timers/hearbeats.