Depends what you are mashing at. I usually only mash for a half hour or so, but with wheats and low mash temps I go longer. Long enough for conversion but sometimes I will just let her sit for 90 minutes. Just mashed a Patersbier (all pils malt) at 147 for 90 minutes b/c I didn't bother with checking for conversion as time was not an issue. Looks like the recipe is suggesting 145 as a mash temp. I would go 90 minutes with that and make sure you are keeping the temp at 145 by adding quarts of boiling water to keep the temp up. That is if you do not have a direct fired tun.
Kegged: Millenium Galaxy IPA, German Pilsner. Apricot Blonde Ale, ACE Witbier, ACE American Wheat.
Bottled: Smoked Red Rye, Old Tanglefoot Barleywine, Tripel, Dubbel, American Farmhouse Ale