Problems associated with implementations of "confusing and complicated" procedural modifications and adjustments can best be mitigated by carefully developed and presented detailed, and well explained, instructions. Hopefully, although that that has yet to be provided for the conversion to a 40 second play clock, relevant instructions and mechanic revisions will be released in a timely manner long enough preceding the 2019 Season to provide ample opportunity to apply these revisions prior to play beginning, in the multiple configurations necessary.
Unlike other levels of American football, a majority of Interscholastic playing facilities currently subject to NFHS Rules, DO NOT routinely provide "Field-Level play clocks", presenting the challenge of incorporating these revisions from a field level, which in many circumstances will be managed by a variety of 3, 4 and 5 man field officiating crews.
Considering the variety of circumstances subject to this timing revision, instructional mechanics protocols, as far in advance of game application, becomes more of a necessity to avoid confusion and interruption. This is a classic example of "One size not fitting ALL", and it seems unrealistic that anticipated consistency in the various venues will occur prior to the 2019 season, Nationwide.
Perhaps the existing alternative, to revising the entire "play clock" application, of appropriately tightening existing mechanics, and timing procedures, to reduce and/or eliminate those unnecessary and excessive delays allowed to persist due to currently ineffective, but correctable, game management lapses and lack of officiating supervision and enforcement should be addressed more directly, consistently and emphatically to accomplish equal, or better, improvements in overall duration of game time, to address the objective, to address the issue of extended game duration.