I think this is an interesting idea, but doesn’t really intersect with the main post. The marginal benefits of reaching a galaxy earlier are very very huge. This means that if we are ever in the situation where we have some probes flying away, and we have the option right now to build faster ones that can catch up, then this makes the old probes completely obsolete even if we give the new ones identical instructions. The (sunk) cost of the old probes/extra new probes is insignificant compared to the gain from earlier arrival. So I think your strategy is dominated by not sending probes that you feel you can catch up with later.
I think this is an interesting idea, but doesn’t really intersect with the main post. The marginal benefits of reaching a galaxy earlier are very very huge. This means that if we are ever in the situation where we have some probes flying away, and we have the option right now to build faster ones that can catch up, then this makes the old probes completely obsolete even if we give the new ones identical instructions. The (sunk) cost of the old probes/extra new probes is insignificant compared to the gain from earlier arrival. So I think your strategy is dominated by not sending probes that you feel you can catch up with later.