George,
Prior to about a week ago, my routine was a 50/200CR plus a whole plain 25/100 first thing in the morning; this got me "kick-started" in about 20-30 minutes, and lasted at least 7 hours, around 3:00 pm, at which time I took another 50/200CR plus one half a regular 25/100. This kept me going pretty well until 9-10:00 pm.
Last week I began substituting a whole 25/100CR for the afternoon half a regular 25/100. This gently "bumped up" regimen seems to keep me going stronger later in the evening.
Robert