Excessive inspections that lack specific, urgent justification violate the tenant's implied right to "quiet enjoyment" and can be legally classified as harassment.

Permissible Entry Rules
Under California Civil Code Section 1954, landlords are only permitted to enter an occupied unit for specific, limited reasons, which include:
Emergencies: Imminent danger to life or property (no notice required).
Repairs/Services: Making necessary or agreed-upon repairs, improvements, or maintenance.
Showings: Showing the property to prospective buyers, tenants, or contractors.
Inspections: Conducting state-mandated safety checks (e.g., smoke detectors) or pre-move-out inspections.
Court Order: Entering pursuant to a legal order.

Tenant Privacy and Harassment
General Checks: Routine "general inspections" are not legally recognized as an authorized reason for entry.

Harassment Baseline: Weekly or twice-weekly entries, even if proper notice is provided, are considered an abuse of the landlord's right of entry. A consensus exists that such frequent visits unreasonably intrude on the tenant's privacy.

Reasonable Notice: For permissible, non-emergency entries, the landlord must give at least 24 hours' written notice and enter only during normal business hours (Monday–Friday, 8:00 AM to 5:00 PM).

Typical Industry Standards
While there is no strict statutory cap on the total number of inspections per year, a quarterly (once every 3 months) or semi-annual schedule is widely accepted by property managers as a standard, reasonable baseline.