Hi Imms,
There are at least 3 replies on same subjects, as far as I remember, advising to use the advanced parameters of typology rules:
'Email Marketing pressure' limitation feature
Typology Rules
Re: Limit an amount of three emails sent per day to one recipient
Of course, the typology rule pressure fields allow a lot of flexibility but are based on database fields criteria (so more or less underlying SQL expressions).
If you really need to use Javascript for a reason or another, I strongly recommend you to calculate the weights but let the engine behaves as standard, not developing at the delivery level itself (such as delivery work tables).
Regards
J-Serge