The most common source of delay is an incomplete submission, not a backlog: missing egress window details on a basement conversion, or an unclear fire separation plan on a secondary suite, sends the file back for revisions and restarts part of the clock.
Renovations that touch structural elements, add a secondary suite, or change the building's footprint generally take longer to review than cosmetic work like new flooring or a kitchen refresh that does not require a permit at all.
Confirming what actually needs a permit before you start work avoids the more expensive problem of unpermitted renovations discovered later. Get your hand-reviewed valuation from Joel Dyck.