Best way to evaluate whether to Bid any Reserve period is to take a look at what's going on in the current month.
Can get an idea by looking at someone's calendar who's close to your relative Seniority...or take a gander at the Reserve Leveling page on VIPs-but that's more of a snapshot which might\might not be all that helpful.
Things to consider, we're coming into Summer where people actually Tend to use all their vacation and maximize days off so VTO's tend to be a bit better.
And SL utilization is likely lower (at least I've tended to be ill over winter months with flu\cold symptoms)
Also, as commented, next month the Company is soliciting Vacation buyback.