If you're an FO on the 175 and don't want to be forced upgraded to the 145, it makes sense to slow play your flight time by bidding reserve at least some if you don't have 800 hours yet.

OH! And the 800 hour part only applies through Feb 28 so no reason to even worry the LOA that forces 800-950 hour FOs to fly anymore. So if you want to delay upgrade, bid reserve even if you already have 800 hours.