My experiences with clients and backlog are more along the lines of
1) Is this work planned, ie > 90%, meaning craftcode, men, est.hours
2) The amount of backlog hours by craft is not necessarily something that you can control - unless the Maintenance Manager decides to 'knock it down' by bringing in temporary staff
3) The purpose of planning is to be able to Schedule work. This is the end game - and where the ROI is.
4) Opportunistic scheduling is also a best practice
5) Backlog should be prioritized using a combination of Workorder Priority and Asset Priority (RPN)

Backlog is not necessary bad. Too much or too little backlog is bad. Just the right amount of backlog hours is good. The aim is to manage and control backlog hours to about 2 to 2.5 crew-weeks with all things ready for jobs to be executed i.e. front-end loading for the workers. If somehow the backlog accumulates to higher than this e.g. due to unexpected shutdowns, then maybe need to bring in extra manpower to level the amount of backlog.