When it makes more sense to do so
Remember, the primary purpose of the document is to communicate; concisely and unambiguously - the drafting should be structured to best support that purpose.
For your problem
You're both wrong. The constitution needs to deal with elected officials - it shouldn't concern itself with particular standing boards and subcommittees.
Set up the rules for committees and allow the management committee (or whatever its called) to establish and dissolve subcommittees at its discretion. A "annual fete" committee might make sense now but in 15 years time when you no longer hold them its just silly to still have it in the constitution. Similarly, just because you have a committee of 8 now doesn't mean that that will always be the best number.
Basically, don't lock in current practices - just because they work now doesn't mean they will always work and its way easier to change a practice by a committee resolution than by having to redraft the constitution ... again! As a foundational document it should only need to deal with high level issues like elections, dispute resolution, membership and management structure (rather than management practice).
A few points to remember
Status of the constitution
Your constitution is a (quasi-)contract, not a constitution.
- That your church is subject to whatever state or national laws allow for your church to exist as an organisation. For example, in NSW, Australia the relevant law is the ASSOCIATIONS INCORPORATION ACT 2009. You should start with whatever legislation applies to you to make sure your constitution is in compliance with it. If it isn't then it isn't a valid constitution.
- Unlike a national constitution it can be externally enforced. That is, if the office bearers are breaking the rules someone can go to court to stop them. National constitutions must be internally enforced - a sufficiently powerful national office bearer can simply "nope" the court.
Reference that law, don't copy it
Laws change, if you have copied large swathes of it into your constitution then your constitution becomes invalid when they do.
Don't redefine things the law deals with - if the law defines "officers" and "committees" don't come up with your own definitions for these things: adopt those (by reference).
Use a template
Check the applicable legislation - it is not uncommon for it to incorporate a "model constitution", for example. If you start with this you have the advantage of knowing that it starts complying with the law and will be relatively common and familiar across many organisations; lowering the learning curve for new members/executives.
Write in plain English
Keep it legal
This doesn't just mean complying with legislation - it also means complying with common law principles like natural justice and procedural fairness. For example, if your constitution deals with disciplinary matters like expelling members, people are entitled to a fair hearing and an appeal.
Have a dictionary
For terms with a definite meaning define these (by reference if appropriate) in one place at the start of the document - don't make people flick to the back just to work out what "sub-committee" means. Even better, put the document online as web pages with hyperlinks.
Resist the temptation to be overly prescriptive or limiting on current or future office bearers/committees - trust them to act responsibly. You guys are reasonable people - why to you think your replacements won't be?
For example, don't set hard discretionary spending limits, set a rule which allows the management committee to set these at their discretion. After all the committee in 2047 is going to be in a better position to deal with the issues of 2047 than you are.
The constitution is a document that should enable the organisation to act, not prevent it from acting.